sfra user guide

PN 500-0590 72A-2570-01 Rev. E 06/06

Doble SFRA User Guide

Doble Engineering Company 85 Walnut Street

Watertown, Massachusetts 02272-9107 (USA)

Telephone: (617) 926-4900

Fax: (617) 926-0528 www.doble.com


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NOTICE This User Guide (the “User Guide”) is solely the property of the Doble Engineering Company (Doble®) and, along with the subject matter to which it applies, is provided for the exclusive use of Doble Users (the “User”) under contractual agreement for Doble® test equipment and services. In no event does the Doble Engineering Company assume liability for any technical or editorial errors of commission or omission; nor is Doble liable for direct, indirect, incidental, or consequential damages arising out of reliance, inaccurate third party information or the inability of the User to use this User Guide properly. Copyright laws protect this User Guide; all rights are reserved. No part of this User Guide shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise without written permission from the Doble Engineering Company. Doble and the Doble logo are registered in the U.S. Patent and Trademark Office and are trademarks of the Doble Engineering Company. Doble® is providing the information contained herein for reference purposes only. Doble® makes no warranty or representation that the User Guide will meet the User’s requirements. This User Guide is intended to provide a basic understanding and general application of the principles set forth herein. Comments contained herein relating to safety represent minimum guidelines, and should never be compromised; however, it is foreseeable that the minimum safety guidelines may be supplemented in order to conform to User’s company safety and compliance regulations. User is responsible for applying the information contained herein in strict accordance with industry as well as User’s company compliance and safety regulations. The techniques and procedures described herein are based on years of experience with some tried and proven methods. However, the basic recommendations contained herein cannot cover all test situations and there may be instances when Doble® should be consulted directly. Doble® is not responsible for the MISUSE OR RELIANCE ON THIS PUBLICATION; ANY OPINIONS CONTAINED HEREIN OR AS A RESULT OF MODIFICATION BY ANYONE OTHER THAN DOBLE® OR AN AUTHORIZED DOBLE REPRESENTATIVE.

THERE ARE NO WARRANTIES, EXPRESSED OR IMPLIED, MADE WITH RESPECT TO THIS USER GUIDE INCLUDING, BUT NOT LIMITED TO, ANY IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. DOBLE® EXPRESSLY DISCLAIMS ALL WARRANTIES NOT STATED HEREIN. IT IS UNDERSTOOD THAT MUCH OF THIS INFORMATION (ALTHOUGH OWNED BY DOBLE®) HAS BEEN COMPILED FROM OR CONVEYED BY THIRD PARTIES WHO IN DOBLE’S REASONABLE ASSESSMENT ARE LEADING AUTHORITIES IN THE INDUSTRY, ALTHOUGH DOBLE HAS REVIEWED THE INFORMATION WITH REASONABLE CARE, THE VERACITY AND RELIABILITY OF THE INFORMATION AND IT’S APPLICATION IS NOT ABSOLUTE. UNDER NO CIRCUMSTANCES WILL DOBLE BE LIABLE TO USER OR ANY PARTY WHO RELIES IN THE INFORMATION FOR ANY DAMAGES, INCLUDING WITHOUT LIMITATION, PERSONAL INJURY OR PROPERTY DAMAGE CAUSED BY THE USE OR APPLICATION OF THE INFORMATION CONTAINED HEREIN, ANY INCIDENTAL OR CONSEQUENTIAL DAMAGES, EXPENSES, LOST PROFITS, LOST SAVINGS, OR OTHER DAMAGES ARISING OUT OF THE USE OF OR INABILITY TO USE THIS INFORMATION SUCCESSFULY. Some states do not allow the limitation or exclusion of liability for incidental or consequential damages, so the above limitation or exclusion may not apply.

© Copyright, 2006

By DOBLE ENGINEERING COMPANY

All Rights Reserved


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TABLE OF CONTENTS

Chapter 1 Introduction .................................................................................................................1

Chapter 2 Parts List – Hardware and Software .........................................................................3 2.1. M5200 SFRA Instrument Hardware..........................................................................3 2.2. M5300 SFRA Instrument Hardware..........................................................................4 2.3. M5200 & M5300 Test Cables ...................................................................................5 2.4. Instrument Safety/Chassis Ground ............................................................................6 2.5. Other Accessories ......................................................................................................6

2.4.1 Large Cable Clamps..................................................................................6 2.4.2 Test lead ground extensions......................................................................6

2.6. Software.....................................................................................................................6

Chapter 3 SFRA Theory ...............................................................................................................7

Chapter 4 Safety and Personnel ...................................................................................................9 4.1. Safety .........................................................................................................................9 4.2. Safety – General Rules ..............................................................................................9 4.3. Grounding................................................................................................................10 4.4. Personnel Safety ......................................................................................................10

Chapter 5 SFRA Test Preparations ...........................................................................................11 5.1. Preparing the Transformer.......................................................................................11 5.2. Preparing the Doble SFRA Instrument....................................................................12 5.2.1. Preparing the M5300 SFRA Instrument..................................................................12 5.2.2. Preparing the M5200 SFRA Instrument and PC .....................................................12 5.3. Check test leads .......................................................................................................13 5.4. Connect Test leads to transformer ...........................................................................14 5.5. Perform a test...........................................................................................................14 5.6. Powering Down the Doble SFRA Instrument .........................................................14

Chapter 6 Software ......................................................................................................................15 6.1. Overview .................................................................................................................15 6.2. Installation on a PC .................................................................................................15 6.3. Running the Software ..............................................................................................16

6.3.1. Connect to an Instrument? ......................................................................16


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6.3.2. Main Window .........................................................................................17 6.4. Menu Options ..........................................................................................................19

6.4.1. File ..........................................................................................................19 6.4.2. Edit..........................................................................................................19 6.4.3. Test Init ...................................................................................................19 6.4.4. Graph.......................................................................................................20 6.4.5. Help.........................................................................................................21

6.5. Window Tabs...........................................................................................................21 6.5.1. Magnitude ...............................................................................................22 6.5.2. Phase .......................................................................................................22 6.5.3. Sub-band Magnitude...............................................................................23 6.5.4. Waveform ...............................................................................................24 6.5.5. Analysis ..................................................................................................25 6.5.6. Tabulation ...............................................................................................26 6.5.7. Apparatus ................................................................................................27 6.5.8. Data Manager..........................................................................................27

6.6. Apparatus/Test and Legend Sub-Panes ...................................................................29 6.6.1. Apparatus/Test Sub-window...................................................................29 6.6.2. Legend Sub-window ...............................................................................30

6.7. Apparatus Details – Review, Edit, New, Delete, ....................................................32 6.7.1. Accessing Apparatus Details ..................................................................32 6.7.2. Location, Test Equipment and Test Organization Editors......................33 6.7.3. Importing and Exporting Location Files.................................................36 6.7.4. Transformer Editor..................................................................................37

6.8. Test Templates.........................................................................................................44 6.8.1. Accessing Templates ..............................................................................45 6.8.2. Review Templates...................................................................................45 6.8.3. Creating a New Template .......................................................................47 6.8.4. Managing Tests in a Template................................................................48 6.8.5. Deleting a Template................................................................................49 6.8.6. Template Files.........................................................................................49 6.8.7. Importing a Set of Templates..................................................................50 6.8.8. Associating a Template with a Transformer...........................................50

6.9. Data Management....................................................................................................50 6.9.1. Data Source.............................................................................................51 6.9.2. Data Manager..........................................................................................52


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6.9.3. Selecting a Data Source ..........................................................................53 6.9.4. Refresh Data Tree ...................................................................................53 6.9.5. Displaying Traces (Results)....................................................................53 6.9.6. Selecting a Subset of Results for Display...............................................54 6.9.7. Exporting Results to a CSV file..............................................................56 6.9.8. Importing Location and Transformer from Results Files .......................56

6.10. Importing 1.x and 2.x M5100 SFRA Files ..............................................................58 6.11. Running a Test.........................................................................................................59

6.11.1. Select Apparatus .....................................................................................59 6.11.2. Set Test Group Parameters .....................................................................60 6.11.3. Select Test from Associated Template ...................................................61 6.11.4. Start Test .................................................................................................61 6.11.5. Test in Progress.......................................................................................64 6.11.6. Checking Results and Trouble Shooting Results....................................66

6.12. Saving and Deleting Traces.....................................................................................70 6.12.1. Saving Traces..........................................................................................70 6.12.2. Deleting Traces .......................................................................................70

6.13. Transferring Data between Machines or PC’s.........................................................70 6.14. Merging Settings Files.............................................................................................71

6.14.1. Opening a Settings File...........................................................................71 6.14.2. A Merge Example ...................................................................................72 6.14.3. Merging Caveats .....................................................................................73

6.15. Application Details ..................................................................................................74 6.15.1. Graph Options.........................................................................................74 6.15.2. Pan...........................................................................................................79 6.15.3. Analyze ...................................................................................................79 6.15.4. Printing and Reporting............................................................................84

6.16. Closing the Software ...............................................................................................86

Chapter 7 Application – Connections ........................................................................................88 7.1. Measurement Types.................................................................................................88

7.1.1. Open Circuit............................................................................................88 7.1.2. Interwinding............................................................................................88 7.1.3. Short Circuit............................................................................................89

7.2. Test Templates.........................................................................................................89 7.3. Two Winding Transformers ....................................................................................90


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7.4. AutoTransformers....................................................................................................90 7.5. Three Winding Transformers ..................................................................................91

Chapter 8 Examples.....................................................................................................................92 8.1. Three Responses for One Transformer....................................................................92 8.2. HV Delta Response .................................................................................................93 8.3. HV Wye (star) Response .........................................................................................94 8.4. Short Circuit Test Response ....................................................................................95 8.5. Repeat Results for One Phase at Different Times ...................................................96 8.6. Results Showing a Shorted Turn .............................................................................96

Chapter 9 Data Interpretation....................................................................................................98 9.1. Frequency-dependant Transformer Equivalent Circuit ...........................................98 9.2. Diagnostic Significance of Frequency Ranges........................................................99

9.2.1. Per-phase Open Circuit Measurement ....................................................99 9.2.2. Short Circuit Measurement ...................................................................101

9.3. Analysis of Test Data ............................................................................................102 9.3.1. Initial Measurement ..............................................................................102 9.3.2. Subsequent Measurement .....................................................................102 9.3.3. Other Diagnostic Measurements...........................................................103

Chapter 10 Application Notes..................................................................................................106 10.1. Short Circuit Lead Responses ...............................................................................106 10.2. Open Circuit Lead Responses ...............................................................................107 10.3. Cable Length .........................................................................................................107

Chapter 11 Technical Support and Troubleshooting.............................................................110 11.1. PC ..........................................................................................................................110 11.2. Installing Software on a PC...................................................................................110 11.3. Running Your First Test ........................................................................................110 11.4. Checking Communication between PC and M5200..............................................110 11.5. Field repairs ...........................................................................................................110 11.6. Parts List ................................................................................................................111

Chapter 12 References...............................................................................................................116

Chapter 13 Miscellaneous .........................................................................................................120


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Table of Figures Figure 1 M5200 Test Set and Accessories...................................................................................... 3 Figure 2 M5200 SFRA Instrument Front View.............................................................................. 4 Figure 3 M5300 Test Set and Accessories...................................................................................... 4 Figure 4 M5300 SFRA Instrument Front View.............................................................................. 5 Figure 5 Safety Ground................................................................................................................... 6 Figure 6 Two Port Network ............................................................................................................ 7 Figure 7 Connecting Safety Ground to Transformer .................................................................... 10 Figure 8 Connect to M5200 .......................................................................................................... 12 Figure 9 No SFRA instrument found............................................................................................ 13 Figure 10 M5200 found – communication blocked...................................................................... 13 Figure 11 Doble SFRA Software Start Up Screen ....................................................................... 16 Figure 12 Connect to M5200 ........................................................................................................ 16 Figure 13 Connected to M5200 .................................................................................................... 17 Figure 14 Connection Not Attempted........................................................................................... 17 Figure 15 Main Software Screen .................................................................................................. 18 Figure 16 File Menu Option ......................................................................................................... 19 Figure 17 Edit Menu Option......................................................................................................... 19 Figure 18 Test Menu Option......................................................................................................... 20 Figure 19 Graph Menu Option...................................................................................................... 20 Figure 20 Help Menu Option........................................................................................................ 21 Figure 21 Help… About ............................................................................................................... 21 Figure 22 Magnitude Chart........................................................................................................... 22 Figure 23 Phase Chart................................................................................................................... 23 Figure 24 Sub-Band Charts........................................................................................................... 23 Figure 25 Waveform Display........................................................................................................ 24 Figure 26 Analysis Tab................................................................................................................. 25 Figure 27 Tabulation Tab ............................................................................................................. 26 Figure 28 Apparatus Tab .............................................................................................................. 27 Figure 29 Data Manager Tab ........................................................................................................ 28 Figure 30 Apparatus and Test Sub-window ................................................................................. 29 Figure 31 Legend Sub-window..................................................................................................... 30 Figure 32 Plot property Command ............................................................................................... 31 Figure 33 Plot Property Dialog..................................................................................................... 31 Figure 34 Edit Apparatus Menu.................................................................................................... 32 Figure 35 Test Equipment Panel................................................................................................... 33 Figure 36 Editors and Details ....................................................................................................... 34 Figure 37 Reviewing/Editing Location Data – A ......................................................................... 35 Figure 38 Reviewing/Editing Location Data – B ......................................................................... 35 Figure 39 Entering a New Location.............................................................................................. 35 Figure 40 Deleting a Location ...................................................................................................... 36 Figure 41 Exporting Location Entries to a File ............................................................................ 36 Figure 42 Exporting Location Folder Selection ........................................................................... 37 Figure 43 Importing Location Entries from a File........................................................................ 37 Figure 44 Reviewing/Editing Transformer Data – A ................................................................... 38 Figure 45 Reviewing/Editing Transformer Data – B.................................................................... 39


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Figure 46 Reviewing/Editing LTC/DETC Data ........................................................................... 40 Figure 47 Reviewing Test Template Association......................................................................... 41 Figure 48 Selecting a Test Template ............................................................................................ 42 Figure 49 Entering a New Transformer ........................................................................................ 43 Figure 50 Deleting a Transformer ................................................................................................ 44 Figure 51 Reviewing Available Test Templates........................................................................... 45 Figure 52 Reviewing Available Test Templates........................................................................... 46 Figure 53 Creating a New test Template ...................................................................................... 47 Figure 54 Managing Tests in a Template ..................................................................................... 48 Figure 55 Adding a New Test to a Template................................................................................ 48 Figure 56 Deleting a Test from a Template .................................................................................. 49 Figure 57 Deleting a Template ..................................................................................................... 49 Figure 58 Associating a Template with a Transformer ................................................................ 50 Figure 59 Options Menu ............................................................................................................... 51 Figure 60 Data Sources................................................................................................................. 51 Figure 61 Selecting Data Source Location ................................................................................... 52 Figure 62 Opening the Data Manager........................................................................................... 52 Figure 63 Selecting Data Source .................................................................................................. 53 Figure 64 Confirmation of Data Source Being set as Default ...................................................... 53 Figure 65 Available Results.......................................................................................................... 54 Figure 66 Selecting Results by Directory Tree............................................................................. 54 Figure 67 Selecting a Single Result for Display........................................................................... 55 Figure 68 Highlighting Results for Display.................................................................................. 55 Figure 69 Choosing a Folder for CSV Export .............................................................................. 56 Figure 70 Saving File in CSV Confirmation ................................................................................ 56 Figure 71 Confirmation of Transformer Import ........................................................................... 57 Figure 72 Confirmation of no Location Imports........................................................................... 57 Figure 73 Selecting a Transformer Location Combination .......................................................... 59 Figure 74 Setting Test Parameters ................................................................................................ 60 Figure 75 Choosing a Test from a Template ................................................................................ 61 Figure 76 Test Details................................................................................................................... 61 Figure 77 Test Details if no Template was Used.......................................................................... 62 Figure 78 Red-Black Lead Locations are Required Fields........................................................... 63 Figure 79 Test in Progress ............................................................................................................ 64 Figure 80 Self Test - Temperature ................................................................................................ 65 Figure 81 Self Test – Noise .......................................................................................................... 65 Figure 82 Self Test – Ground Continuity ..................................................................................... 65 Figure 83 Self Test – Signal Generation....................................................................................... 66 Figure 84 Waveforms ................................................................................................................... 67 Figure 85 Typical Open Circuit Response................................................................................... 68 Figure 86 Open Circuit in Red Test Lead..................................................................................... 69 Figure 87 Open Circuit in Test Lead Dialog Box......................................................................... 69 Figure 88 Graph Options Menu .................................................................................................... 74 Figure 89 Clicking on Cursor 1 .................................................................................................... 74 Figure 90 Two Cursors Displayed – Red and Blue ...................................................................... 75 Figure 91 Centered Cursors .......................................................................................................... 75


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Figure 92 Plot Range Dialog Box................................................................................................. 76 Figure 93 Graph using Default Log Scale .................................................................................... 77 Figure 94 Graph with Linear Scale............................................................................................... 78 Figure 95 Clear Traces Dialog Box .............................................................................................. 78 Figure 96 Analysis Display........................................................................................................... 79 Figure 97 Analysis - Select Traces Dialog Box............................................................................ 80 Figure 98 Incorrect Number of Traces Selected........................................................................... 80 Figure 99 Analysis of Two Traces................................................................................................ 81 Figure 100 User Defined Difference Limits ................................................................................. 81 Figure 101 Difference Plot ........................................................................................................... 82 Figure 102 Edited Difference Plot Values .................................................................................... 82 Figure 103 Difference Plot with New Limits ............................................................................... 82 Figure 104 Correlation Range Display ......................................................................................... 82 Figure 105 Correlation Range Selections ..................................................................................... 83 Figure 106 Correlation Coefficients ............................................................................................. 83 Figure 107 Correlation Limits ...................................................................................................... 83 Figure 108 File Menu – Print and Print Preview.......................................................................... 84 Figure 109 Print Preview Dialog Box........................................................................................... 84 Figure 110 Print Preview Details Page ......................................................................................... 85 Figure 111 Windows Print Dialog Box ........................................................................................ 86 Figure 112 Exit Software Confirmation ....................................................................................... 86 Figure 113 Actions before Restoring Network Connections........................................................ 87 Figure 114 Responses for One Phase of a Transformer ............................................................... 92 Figure 115 HV Delta Winding Responses.................................................................................... 93 Figure 116 HV Wye Winding Response ...................................................................................... 94 Figure 117 Short Circuit Test Response ....................................................................................... 95 Figure 118 Short Circuit Response – Detail ................................................................................. 95 Figure 119 Repeat Results for One Phase .................................................................................... 96 Figure 120 Shorted Turn on one Winding .................................................................................... 97 Figure 121 Per-Phase Measurement –Magnitude of the Transfer Function................................. 99 Figure 122 Per-Phase Measurement – Phase of the Transfer Function...................................... 100 Figure 123 T Model of Transformer Winding............................................................................ 101 Figure 124 T Model with LV Short ............................................................................................ 101 Figure 125 Short Circuit Lead Response.................................................................................... 106 Figure 126 Open Circuit Lead Response.................................................................................... 107 Figure 127 Front View of M5300.............................................................................................. 112 Figure 128 Front Panel Assembly, CPU PC Board, and Fan .................................................... 112 Figure 129 Power Supply - +5V, + 12V Output........................................................................ 113 Figure 130 CPU Module Assembly........................................................................................... 113 Figure 131 Assembly, PCB + 15V Converter ........................................................................... 114 Figure 132 High Density Drive, 20GB IDE .............................................................................. 114 Figure 133 PPC4/Analog Module Assembly............................................................................. 115 Figure 134 USB Keyboard......................................................................................................... 115


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Table of Tables

Table 1 Transformer Settings XML Format ................................................................................. 71 Table 2 User A Transformer Settings XML File .......................................................................... 72 Table 3 User B Transformer Settings XML File .......................................................................... 72 Table 4 Transformer Nameplate Section from User B File.......................................................... 73 Table 5 Two Winding Transformers............................................................................................. 90 Table 6 Autotransformers ............................................................................................................. 90 Table 7 Three Winding Transformers – Part 1 ............................................................................. 91 Table 8 Three Winding Transformers – Part 2 ............................................................................. 91 Table 9 Diagnostic Tests............................................................................................................. 104 Table 10 Minimum PC Requirements ........................................................................................ 110 Table 11 Parts List ...................................................................................................................... 111


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Chapter 1 Introduction Sweep Frequency Response Analysis (SFRA) testing has become a valuable tool for verifying the geometric integrity of electrical apparatus, especially transformers. The SFRA technique provides internal diagnostic information using non-intrusive procedures. Over the last ten years, only the SFRA test method has been proven to provide accurate and repeatable measurements, with Doble providing the back up and support necessary to extract value from the measurement. Power transformers are specified to withstand the mechanical forces arising from both shipping and subsequent in-service events, such as faults and lightning. Transportation damage can occur if the clamping and restraints are inadequate; such damage may lead to core and winding movement. The most severe in-service forces arise from system faults, and are axial and radial in nature. If the forces are excessive, radial buckling or axial deformation can occur. With a core form design the principal forces are radially directed, whereas in a shell form unit they are axially directed, and this difference is likely to influence the types of damage found. Once a transformer has been damaged, even if only slightly, the ability to withstand further short circuits is reduced. Utility personnel need to effectively identify such damage. A visual inspection is costly and does not always produce the desired results or the correct conclusion. During a field inspection, the oil has to be drained and confined entry rules apply. Since so little of the winding is visible, little damage is seen other than displaced support blocks. Often, a complete tear down is required to identify the problem. An alternative method is to implement field-diagnostic techniques capable of detecting damage. There is a direct relationship between the geometric configuration and the distributed electrical elements, otherwise known as RLC networks, of a winding and core assembly. This RLC network can be identified by its frequency-dependent transfer function. Frequency Response Analysis testing can be accomplished by the sweep frequency method (SFRA). Changes in the geometric configuration alter the impedance network, and in turn alter the transfer function. Changes in the transfer function will reveal a wide range of failure modes.


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Chapter 2 Parts List – Hardware and Software The M5200 and M5300 have different components, as shown below.

2.1. M5200 SFRA Instrument Hardware The M5200 SFRA Instrument comes complete with packaged hardware, software, and cables, as shown in Figure 1. This section provides an introduction to the various parts and accessories that comprise the M5200 SFRA Instrument.

Figure 1 M5200 Test Set and Accessories

The M5200 SFRA Instrument measures and records the frequency response characteristics of transformer windings. It accomplishes this using the various hardware components packaged in a rugged field instrumentation/controller module, an excitation source, and a measurement module, packaged in a robust molded shell, as shown in Figure 2.


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Figure 2 M5200 SFRA Instrument Front View

2.2. M5300 SFRA Instrument Hardware The M5300 SFRA Instrument comes complete with packaged hardware, software, and cables, as shown in Figure 1. This section provides an introduction to the various parts and accessories that comprise the M5300 SFRA Instrument.

Figure 3 M5300 Test Set and Accessories

The M5300 SFRA Instrument measures and records the frequency response characteristics of transformer windings. It accomplishes this using the various hardware components packaged in a

Color coded test lead connectors

Chassis Ground

Power Switch and Indicator

System Status Indicators

Communication Ports


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rugged field instrumentation/controller module, an excitation source, and a measurement module, packaged in a robust molded shell, as shown in Figure 2.

Figure 4 M5300 SFRA Instrument Front View

2.3. M5200 & M5300 Test Cables

The cables and connectors supplied with the M5200 and M5300 should not be modified in any manner. The test leads are made from low loss RG-58 RF coaxial cable with the shields grounded to the instrument chassis through a standard connector. The SFRA Instrument requires a matched impedance signal cable, and performs a single end measurement, that is, the signal is measured with respect to the instrument ground. The shield of the signal cable must be connected to the chassis using a 50 Ohm impedance-matched RF BCN connector. Practical field experience indicates that the leads be 60 ft. in length. This length is the shortest length useful to test the largest transformers from a location on the ground, adjacent to the unit. Nevertheless, it is the lead length that determines the maximum effective frequency. Cable Shield Grounds - used to connect cable shield to the transformer ground at the base of the bushing. These ground connections are located 12 ft. (3.7m) back from the terminal connection on the measurement ends of the cables.


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2.4. Instrument Safety/Chassis Ground

Grounding of signal cable shields, specimen, and instrument chassis is important to achieving a reproducible result.

Figure 5 Safety Ground The Safety Ground, also known as the instrument Chassis Ground, shown in Figure 5, is used to connect the instrument chassis to the ground of the transformer.

2.5. Other Accessories

2.4.1 Large Cable Clamps These clamps are used to make connections to larger bushing studs or terminals where the normal connectors do not fit. The standard test cables then clip to the large clamps.

2.4.2 Test lead ground extensions In those cases where the 12 feet (3.7m) of ground is not enough to reach from the bushing terminal to the base of the bushing, the white ground extension leads are used to provide extra length.

2.6. Software

The M5200 SFRA test set is controlled by a user supplied lap top.

The M5300 SFRA test set has the software installed on it before delivery.

The software is discussed in more detail in Section 0.


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Chapter 3 SFRA Theory The primary objective of SFRA is to determine how the impedance of a test specimen behaves over a specified range of frequencies. The impedance is a distributive network of real and reactive electrical components. The components are passive in nature, and can be modeled by resistors, inductors, and capacitors. The reactive properties of a given test specimen are dependent upon and sensitive to changes in frequency. The change in impedance versus frequency can be dramatic in many cases. This behavior becomes apparent when we model the impedance as a function of frequency. The result is a transfer function representation of the RLC network in the frequency domain. Frequency response analysis is generally applied to a complex network of passive elements. For practical purposes, we will only consider resistors, inductors, and capacitors as passive circuit elements, and they are assumed to be ideal. These three fundamental elements are the building blocks for various physical devices, such as transformers, motors, generators, and other electrical apparatus. It is important to understand the difference between the physical device and the mathematical model we intend to use. When large and complex systems are electrically analyzed, we are often faced with a poorly defined distributed network. A distributed network contains an infinite amount of infinitely small RLC elements. For example, transmission lines are generally distributed in nature. It is practical to model such distributed systems by lumping the basic RLC components together, resulting in a lumped network. Lumping elements together for a single frequency is a trivial task, however, when system modeling requires spanning over a significant frequency interval, then producing a suitable lumped model becomes difficult. When a transformer is subjected to SFRA testing, the leads are configured in such a manner that four terminals are used. These four terminals can be divided into two unique pairs, one pair each for the input and the output. These terminals can be modeled in a two-terminal pair or a two-port network configuration. Figure 6 illustrates a two-port network.

Figure 6 Two Port Network Solving for the open-circuit impedance for each lumped element forms the impedances, Z11, Z22, Z12, and Z21. It should be noted that the negative terminals are short-circuited when transformers are tested. The transformer tank is common for both negative and lower terminals. The transformer tank and lead ground shields must be connected together to achieve a common-


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mode measurement. This assures that no external impedance is measured. Applying the connection in this manner helps reduce the effects of noise. It is very important to obtain a zero impedance between the lower or negative terminals to assure a repeatable measurement. The transfer function of an RLC network is the ratio of the output and input frequency responses when the initial conditions of the network are zero. Both magnitude and the phase relationships can be extracted from the transfer function. The transfer function helps us better understand the input/output relationship of a linear network. The transfer function also represents the fundamental characteristics of a network, and is a useful tool in modeling such a system. The transfer function is represented in the frequency domain and is denoted by the Fourier variable H (jω), where (jω) denotes the presence of a frequency dependent function, and ω= 2πf. The Fourier relationship for the input/output transfer function is given by:

( ) ( )( )ωω

ωjVjV

jHinput

output=

When a transfer function is reduced to its simplest form, it generates a ratio of two polynomials. The main characteristics, such as half-power and resonance, of a transfer function occur at the roots of the polynomials. The goal of SFRA is to measure the impedance model of the test specimen. When we measure the transfer function H (jω), it does not isolate the true specimen impedance Z (jω). The true specimen impedance Z (jω) is the RLC network, which is positioned between the instrument leads, and it does not include any impedance supplied by the test instrument. It must be noted that when using the voltage relationship, H (jω) is not always directly related to Z (jω). For Z (jω) to be directly related to H (jω) a current must be substituted for the output voltage and then Ohms Law can be realized. However, SFRA uses the voltage ratio relationship for determining H (jω). Since the SFRA test method uses a 50 Ohm impedance match measuring system, the 50 Ohm impedance must be incorporated into H (jω). The next equation shows the relationship of Z (jω) to H (jω):

Hv(jω) = Vout(jω) /Vin(jω) Often it is useful to plot the magnitude and phase relationship of the transfer function in logarithmic format. The units of magnitude and phase are in the decibels (dB) and degrees, respectively. The magnitude and phase is represented as follows:

( )( ))(tan)(

)(log20)(1

10

ωθ

ω

jHA

jHdBA−=

=

This format takes advantage of the asymptotic symmetry by using a logarithmic scale for frequency. Plotting the phase relationship with the magnitude data will help determine whether the system is resistive, inductive, or capacitive. It is often useful to compare resonance in the magnitude plots with the zero crossings in the phase relationship.


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Chapter 4 Safety and Personnel

4.1. Safety

Safety cannot be overemphasized when working on or around high voltage electrical apparatus. Companies that generate, transmit, distribute, or utilize high voltage electricity should, and do, have precise rules for safe practices and procedures for personnel whose working responsibilities involve testing and maintenance of the various types of high voltage apparatus, and their associated lines, cables and conductors, as well as the associated accessories.

4.2. Safety – General Rules The transformer under test should be completely de-energized and isolated from the power system before performing any SFRA tests using an M5000 series SFRA Instrument. The method of testing a high voltage apparatus (transformer) involves exciting the apparatus with the Doble SFRA Instrument. Care must be taken to avoid contact with the apparatus being tested, it’s associated bushing and conductors, and with the Doble SFRA Instrument cables and connectors. The test crew must make a visual check to ensure that the apparatus terminals are isolated from the power system. Because the apparatus under test may fail, precautions (such as barriers or entrance restrictions to the test area) must be taken to avoid harm in the event of a violent failure. All of your company rules for safe practice in testing must be strictly conformed to, including all practices for tagging and isolating apparatus during testing and maintenance work. State, local, and federal regulations, e.g., OSHA, HSE, may also apply.

Note Company rules and government regulations take precedence over Doble recommendations.

Personal Protective Equipment suitable for electrical testing of transformers is recommended.


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4.3. Grounding

The apparatus under test, its tank or housing, and the Doble SFRA Instrument must be solidly and commonly grounded or earthed. This also applies to any mobile equipment being tested. See Figure 7 for an example safety ground connection.

Figure 7 Connecting Safety Ground to Transformer The Doble SFRA Instrument test cable shields must also be grounded or earthed to the same common point as the instrument. This is usually achieved by attaching the grounds securely to the bushing flange base.

NOTE

Proper grounding techniques are a very important step in safety and in ensuring reliable SFRA test results.

4.4. Personnel Safety

A pretest meeting is recommended. Frequently, other crews will be working on non-test related tasks in close proximity to equipment being tested. The pretest meeting should include all personnel who will be working in proximity to the area where testing will be performed. In this meeting, the tests to be performed, the apparatus and the voltage test levels involved, potential hazards involved with the work, and the individual assignments should all be reviewed with the crew members. Test personnel need to remain aware of the work activity taking place around them and alert to the possibility that non-test personnel may enter the test area. A consistent and uniform set of signals, both visual and verbal, should be agreed upon, and should be followed by all of the crew members during testing. While making the various types of connections involved in the tests, it may be necessary for personnel to climb up on the apparatus, but no one should remain on the apparatus during the test itself.


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Chapter 5 SFRA Test Preparations

SFRA test preparations consist of:

• Preparing the Transformer • Preparing the Doble SFRA Instrument • Creating the Test Files • Connecting the Apparatus

5.1. Preparing the Transformer

The transformer to be tested must be completely isolated from the power system. This requires that all bushings of all windings be disconnected from any bus and insulators. This ensures that the measurements performed are not adversely affected by interference.

We wish to measure only the RLC network of the transformer. In order to maintain consistency and repeatability of measurements, all terminals that are not under test should be isolated and floating. In order to maintain a balanced and symmetrical approach, where a delta winding is completed and grounded external to the transformer tank, the delta should be complete but floating. Such windings are frequently used for regulation; where such windings are grounded internal to the tank, we are forced to leave that ground in place – but we should expect asymmetry in results.

A frequency response could be measured with the remaining terminals grounded, however it could not be compared to a response that was measured with floating terminals since a different RLC response would be measured.


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5.2. Preparing the Doble SFRA Instrument

5.2.1. Preparing the M5300 SFRA Instrument Turn on the power switch located on the front of the M5300 SFRA Instrument The M5300 SFRA software should start up automatically; if your system has been altered, double click on the SFRA icon or begin the program using ‘Start… Run…’.

5.2.2. Preparing the M5200 SFRA Instrument and PC

Turn on the power switch located on the front of the M5200 SFRA Instrument without it being connected to the user PC. The power light should come on. Both LED’s will come on, then go out and finally the ‘System OK’ LED will come on to indicate status as ‘OK’. The M5200 SFRA software should be run on the user PC. Make sure the M5200 SFRA software is installed on the PC hard drive, not a network drive. The PC should not be connected to any network and wireless connections should be turned off; firewalls and virus software should be disabled. These restrictions do not apply if you wish to use the software in viewer mode only and not communicate with an M5200. Double click on the SFRA Icon on the PC Desktop, or use “Programs… Run…” to start the software. When the window shown in Figure 8 appears, connect the M5200 to the PC using either the USB cable or the Ethernet Cable with Crossover adapter.

Figure 8 Connect to M5200 Click ‘yes’ to connect to the M5200. If no communication with the M5200 is possible, the message in Figure 9 is shown.


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Figure 9 No SFRA instrument found It is possible that the M5200 and the PC can communicate but not allow data transfer – as may be the case when a Windows or other firewall is enabled. The message shown in Figure 10 is shown.

Figure 10 M5200 found – communication blocked This message will appear if there is no cable connection between the PC and M5200 or if there are firewalls or virus software enabled which prevent communication.

5.3. Check test leads Connect the test leads to the instrument; these are color coded cables with BNC adapters.

Note Test leads may be damaged either through poor storage, mishandling in application or accidental damage on site. It is important to check the status of the leads before performing a measurement. This can be done by a short circuit leads test as described in the Quick Start Guide.

Short the measurement clips (cable end) on the cables together and the ground clips (middle of cable) together. Do not connect the measurement clips to the ground clips.

Perform a short circuit measurement.


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5.4. Connect Test leads to transformer Connect the safety ground to the Doble SFRA test set and to the ground on the transformer.

Caution To minimize the chance of the conductors becoming energized due to static electricity, Doble Engineering Company recommends attaching all test set leads to the instrument while the other end of the leads are still on the ground. Attaching the leads to the transformer bushings first increases the risk of operator injury.

5.5. Perform a test

Connect test leads to the transformer as per the recommended tests in Section 0.

Perform a test - this consists of three stages: • Initiate a test (F2) • Monitor test in progress • Test finishes or is aborted (F2) It is important to monitor the test in progress to make sure good data is being collected. Response results begin appearing as soon as the test set begins receiving the data and the software continues to plot the results in until the test is complete.

5.6. Powering Down the Doble SFRA Instrument Power down the M5200 using the power switch.

The M5300 is a PC and should be shut down using standard PC practice – use ‘Start… Shut Down’ from the menu bar.


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Chapter 6 Software

The Doble SFRA M5200 & M5300 Instruments come complete with intuitive Windows ™ based software which runs on a standard PC supplied by the user or on the M5300 itself. 256 Mb of RAM are recommended as a minimum.

6.1. Overview The software allows users to make and compare SFRA measurements. The test itself is easy to perform, but it is important that all relevant details are recorded for future reference otherwise it becomes difficult to reproduce test results. It requires a minimum set of details before a measurement can be made:

• Transformer manufacturer and serial number • Test location • Testing organization • M5200/M5300 serial number • Basic test details: lead location and tap positions. Basic information can be set up before performing any tests and saved. Templates of tests are available for use as a guideline with different transformer designs. All traces are automatically saved on completion.

6.2. Installation on a PC The software installs as a standard Windows application. It is not recommended that the software be installed on a network drive or data stored to a network drive. When setting up data paths (Edit… Options…) it is not recommended that data is saved to a network path. If a network path is specified then data will not be saved in the field as the network will not be accessible. When testing in the field using an M5200 the PC where the software is installed should not be connected to any other network and should not have a wireless network enabled (or switched on). Firewall and virus software should be disabled or turned off while making measurements. These may be returned to default settings when using the software as a viewer only and not communicating with an M5200. When closing down the M5200 software a window will appear confirming that you wish to exit the software.


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6.3. Running the Software

On running the software on the PC or an M5300, a Doble SFRA start up screen is shown, similar to that in Figure 11; you may have a later version of the software.

Figure 11 Doble SFRA Software Start Up Screen

6.3.1. Connect to an Instrument? If running the software on a PC, the software will ask whether you wish to connect to an SFRA instrument, as shown in Figure 12.

Figure 12 Connect to M5200


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Click Yes only if: • the M5200 has been turned on • the indicator LED’s show system ready light on, test light off • the M5200 is connected to the PC via USB or Crossover Ethernet cable On connection, a confirmation message appears, similar to that shown in Figure 13.

Figure 13 Connected to M5200 If you click ‘No’, no attempt will be made to connect to an M5200 and the confirmation window shown in Figure 14.

Figure 14 Connection Not Attempted

6.3.2. Main Window The results area, as shown in Figure 15, dominates the main screen. The screen has a number of menu options, which are discussed in Section 6.4, including:

• File • Edit • Test Init • Graph • Help And the tabs on the lower left side of the screen:


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• Apparatus and Test • Legend Individual Window Tabs, are discussed in section 6.5: • Data Manager • Magnitude • Phase • Sub-band • Waveform • Analysis • Tabulation • Apparatus

Figure 15 Main Software Screen


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6.4. Menu Options

Menu options are available ‘point & click’ or through ‘Alt & key’ commands.

6.4.1. File Menu option ‘File, as shown in Figure 16, has four sub-options:

• Print – allows printing of results and associated details • Print Preview – allows for preview of printing • Exit – quits the Doble SFRA software

Figure 16 File Menu Option

Note: there is no ‘Save’ option as all traces are automatically saved on completion of the trace.

6.4.2. Edit The ‘Edit’ menu option has two sub-options, as shown in Figure 17.

Figure 17 Edit Menu Option Edit Apparatus – allows for entry of apparatus, location and template details; see section 6.7. Options – which control sources for data storage and system settings; see section 6.9.

6.4.3. Test Init ‘Test’, as shown in Figure 18 allows selection of apparatus for test. It is only active after the ‘Select Apparatus’ button has been used once to select and Apparatus/Location combination for test purposes.


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Figure 18 Test Menu Option

6.4.4. Graph This menu option controls graph related features, as shown in Figure 19. See section 6.15.1.

Figure 19 Graph Menu Option


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6.4.5. Help The ‘Help’ menu option, as shown in Figure 20, allows access to the help facility, which is not available in this version and to the ‘About’ option which gives the software version and related details.

Figure 20 Help Menu Option Click on ‘About’ to bring up the window shown in Figure 21.

Figure 21 Help… About The software version and build number are given in the upper right corner of the window. If connected directly to an instrument, or if you are using an M5300, the Instrument Firmware Box will show the version number for the instrument firmware and related items. These may be useful in diagnostic situations. Scroll down to reach the firmware version:

6.5. Window Tabs These allow access to different aspects of SFRA measurements. Click on the appropriate tab for access.


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6.5.1. Magnitude As shown in Figure 15, this is the tab, which displays magnitude data. See section 6.11 for information on trace manipulation.

Figure 22 Magnitude Chart

6.5.2. Phase Phase information is plotted on a separate chart, on the phase tab, as shown in Figure 23. Phase is a useful quantity when looking whether a measurement is more inductive or more capacitive. It is rarely used but can occasionally be a useful diagnostic.


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Figure 23 Phase Chart

6.5.3. Sub-band Magnitude The ‘Sub-band’ tab, Figure 24, is given for reasons of historical continuity. Early work on SFRA required results is displayed on charts of 2 kHz, 20 kHz, 200 kHz and 2 MHz. The last three of these are given here as a means to view the data in that format.

Figure 24 Sub-Band Charts


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6.5.4. Waveform The ‘Waveform’ tab, as shown in Figure 25, is useful when monitoring the progress of a measurement: it displays both the reference waveform generated by the test set and the measured wave form of the object under test. When a bad connection is made, it is possible to use the waveform tab to help diagnose the problem, as discussed in Section 0. This tab only provides a waveform when the test is in progress.

Figure 25 Waveform Display


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6.5.5. Analysis The ‘Analysis’ tab, as shown in Figure 26, allows for comparison of two selected traces. The traces must first be shown on the magnitude plot. They can then be analyzed using difference and cross-correlation. Limits have not yet been set on what is an acceptable variation for difference between two traces on the same transformer at a given frequency; likewise, limits have not been set on what are acceptable differences in correlation coefficient in a given frequency range. Both are areas where the international SFRA community is currently undertaking much research. This will be the page where the Doble Expert System for SFRA, SAM ™, (the SFRA Analysis Manager) will appear in a future version of the software. Data analysis is discussed in more detail in Section 0.

Figure 26 Analysis Tab


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6.5.6. Tabulation Data may be viewed purely in a graphical format, as in the magnitude plot, but may also be viewed in tabular form, as shown in Figure 27. By clicking on an entry in the legend at left, the corresponding results consisting of: • Frequency • Magnitude • Phase The values are shown in the table on the right of the window.

Figure 27 Tabulation Tab


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6.5.7. Apparatus The ‘Apparatus’ tab shows information related to the traces displayed on the Magnitude plot – see Figure 28. This allows full details of the test to be viewed, including: • Transformer Details • Apparatus Location • Test Set Up Click on the legend entry for which details are required and they appear in the window to the right.

Figure 28 Apparatus Tab

6.5.8. Data Manager The ‘Data Manager tab allows for display of traces in user defined folders and the recall for display of those traces, as shown in Figure 29. Traces may be stored in the default folders or in user defined folders. A search tree is available to select sub-sets of the data displayed and the spreadsheet of results may be used to select results for display. Details of Data Management are given in Section 6.9.


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Figure 29 Data Manager Tab


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6.6. Apparatus/Test and Legend Sub-Panes The “Apparatus and Test” sub-pane is only useful for field measurements when connected to an M5200.

6.6.1. Apparatus/Test Sub-window This is where a particular transformer is chosen for test, as shown in Figure 30. It allows setting of basic test parameters and initiation of a test. Subsequently, it shows which frequency is being measured and the progress of the test.

Figure 30 Apparatus and Test Sub-window


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6.6.2. Legend Sub-window The legend option, Figure 31, allows control of graph features, such as line width, style and color. By checking or un-checking the tick box at the left of the legend name it is possible to make the trace visible on the chart or invisible. This is particularly useful when comparing a number of traces simultaneously.

Figure 31 Legend Sub-window


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Right click on a trace name in the legend to show the ‘Plot Property’ box as shown in Figure 32.

Figure 32 Plot property Command

Left click on the ‘Plot Property’ box to bring up the properties menu, as shown in Figure 33.

Figure 33 Plot Property Dialog Use the down arrows to show options available for Color, Line Style and width of the plot.

‘Interference Cancellation’ should be left checked unless there is a need to identify noise frequencies specifically within the results. This option is not available with results which were produced using M5100 version 1.x or M5100 version 2.x software.


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6.7. Apparatus Details – Review, Edit, New, Delete,

Before performing a test on any transformer, it is necessary to enter a certain set of minimum details regarding the:

• Transformer • Transformer location • Test set • Testing organization These must be entered before any tests take place: one or two fields suffice to meet the requirements of unique identification for each item.

6.7.1. Accessing Apparatus Details Apparatus details are accessed through the Edit menu, as shown in Figure 34.

Figure 34 Edit Apparatus Menu Click on the ‘Edit Apparatus’ to bring up the Test Equipment panel as shown in Figure 35.


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Figure 35 Test Equipment Panel The three sets of editors on the left side work in the same way as each other -

6.7.2. Location, Test Equipment and Test Organization Editors The set of panels on the left of the Test Equipment panel is used to create, edit, review and delete:

• Locations • Test Equipment (the M5000 series instrument) • Test Organizations


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Figure 36 Editors and Details A Location is any uniquely identifiable place where a transformer SFRA test may take place. As all SFRA tests take place at some location, and many take place on the same transformer at different locations, it is important to record this information as a feature of the SFRA test. A Test Equipment is an M5200 or M5300 test set, uniquely identified by its serial number. A Test Organization is any uniquely identifiable organization, which performs SFRA testing. It is important to record this information as a feature of the SFRA test. The three editors work in identical ways for reviewing, editing adding and deleting entries.

Reviewing/Editing Location, Test Equipment and Test Organization Data Each editor allows review and editing of entries – Location, Test Equipment, Test Organization. Examples here are given for Location, but the others work in the same way. Each entry must have a unique name: this is its key identifier. It is not good practice to try to enter locations with duplicate names. This may lead to unexpected and undesirable consequences when trying to recall data.

Location Editor

Test Organization Editor

Test Equipment Editor

Test Organization Detail

Test Equipment Detail

Location Detail


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By clicking on entries in the list, details for that entry are brought up in the field on the right of the window, as can be seen by comparing data in Figure 37 and Figure 38. To edit data associated with a particular location, simply edit the contents of the fields and click ‘Save and Exit’.

Figure 37 Reviewing/Editing Location Data – A

Figure 38 Reviewing/Editing Location Data – B

Entering a New Location, Test Equipment or Test Organization Click on ‘New’ or type Alt-N. A new entry titled ‘New Location’ appears in the Location list at the left side of the window, as shown in Figure 39. This may be edited as with any other entry.

Figure 39 Entering a New Location


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Deleting a Location, Test Equipment or Test Organization Choose location by clicking on an entry in the Location List. Click Delete; you must confirm the delete via the Dialog box shown in Figure 40. Deleting a location will not delete any of the results associated with that location.

Figure 40 Deleting a Location

6.7.3. Importing and Exporting Location Files The SFRA software allows for importing/exporting of Location files between users. This helps ensure consistency of locations for different users. A similar feature is available for transformers. Use the Ctrl key and left mouse click to highlight a number of entries in the Location list, as shown in Figure 41.

Figure 41 Exporting Location Entries to a File A dialog box appears asking for the name of the file for the exported Locations to be saved in, as shown in Figure 42.


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Figure 42 Exporting Location Folder Selection The file is saved in xml format. When importing Locations from a file, click the “Import from Location File” and open an xml file. If no valid locations are found, the message in Figure 43 appears.

Figure 43 Importing Location Entries from a File

6.7.4. Transformer Editor The ‘Transformer Editor’ is used to create, edit, review and delete ‘Transformers’. To access the Transformer Editor click “Edit Transformers” from the Test Equipment panel, Figure 35. Transformers are not tied to particular locations – ‘Transformers’ and ‘Locations’ are combined when a test is made so that a test is performed on a transformer at a particular location. That location may change on subsequent tests, after relocation of the transformer, say. A transformer is any uniquely identifiable test object. It is, in fact, quite a complicated object consisting of many parts and sub-assemblies: coolers, bushings, tap changers. The transformer editor allows salient information to be entered and recorded.

Reviewing/Editing Transformer Data After clicking on ‘Transformer Editor’ a window similar to that in Figure 44 is shown. This is the main window for Transformer data.


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Transformers presently available are listed in the box on the left of the window. On the right of the window there are three tabs:

• Transformer • LTC/DETC • Test Template Each tab allows access to data related to a particular transformer. Each may be edited independently. Each transformer must have a unique serial number: this is its key identifier. It is not good practice to try to enter transformers with duplicate serial numbers. This may lead to unexpected and undesirable consequences when trying to recall data. By clicking on entries in the list, details for that entry are brought up in the field on the right of the window, as can be seen by comparing data in Figure 44 and Figure 45. To edit data associated with a particular transformer, simply edit the contents of the fields and click ‘OK.

Figure 44 Reviewing/Editing Transformer Data – A


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Figure 45 Reviewing/Editing Transformer Data – B


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Reviewing/Editing LTC/DETC Data Select ‘LTC/DETC’ data by clicking on the ‘LTC/DETC’ tab. This brings up a window similar to that in Figure 46. This tab allows entry of data associated with any LTC or DETC which may be present on the transformer. This data is not ‘required’ data for a test but is useful reference data. The ‘Range’ fields are used to indicate the full range available for the LTC or DETC. The position of these during a test is recorded in a separate table when a test is made.

Figure 46 Reviewing/Editing LTC/DETC Data


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Reviewing Test Template Association An individual transformer may have a ‘Test Template’ associated with it, as shown in Figure 47. See Section 6.8 for details on test templates. A test template allows a collection of tests to be identified and named, for example, a set of tests for a three phase auto transformer. These may then be associated with a transformer through this tab of the transformer editor. A test template gives a list of recommended test for a transformer, but does not constrain the tester to particular tests. It is a guide, rather than a constraint.

Figure 47 Reviewing Test Template Association


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Editing Test Template Association By clicking on select, a list of available templates is given, as shown in Figure 48.

Figure 48 Selecting a Test Template

It is possible to then associate a transformer with any template available. See Section 6.8 for details of entering and editing test templates.


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Entering a New Transformer Click on ‘New’. A new entry entitled ‘NewSerialNumber’ appears in the Transformer list at the left side of the window, as shown in Figure 49. Details may be entered, including giving the new entry an appropriate serial number.

Figure 49 Entering a New Transformer


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Deleting a Transformer To delete a transformer, highlight its entry by clicking on it in the transformer list in the left side of the Transformer Editor window. Then click on ‘Delete’. A Dialog Box asking for confirmation of the delete will appear. Click ‘Yes’ to delete the transformer. Deleting a transformer does not delete any of the results associated with that transformer.

Figure 50 Deleting a Transformer

6.8. Test Templates Test templates are a means of grouping tests for a particular transformer design and are a flexible way of specifying tests for use in the field. A template is used as a guide and is not a constraint. When testing a transformer the user may select tests from the template, specify tests that are not in the template or ignore the template recommendations. Each test describes the test connections and the state of the transformer. A template may be associated with a number of transformers; it may also be created for future reference and not associated with any transformer.


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6.8.1. Accessing Templates To access templates click on ‘Edit Templates’ in the ‘Test Equipment Panel’ menu, as shown in Figure 35.

6.8.2. Review Templates Available templates are listed at the left side of the window. Click on an entry to show tests, which have been predefined for that template. Figure 51 shows available tests for a 3 Phase 2 Winding D-Y transformer.

Figure 51 Reviewing Available Test Templates

By clicking on the next entry, as shown in Figure 52, we see tests available for a 3 phase 2 winding Y-D transformer.


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Figure 52 Reviewing Available Test Templates


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6.8.3. Creating a New Template To create a new template, click on ‘New’ in the Template Editor. A new entry, ‘New template’ will appear in the list in the window on the left, as shown in Figure 53.

Figure 53 Creating a New test Template To add tests to the template, see Section 6.8.4


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6.8.4. Managing Tests in a Template The template editor allows the user to add, edit or delete tests in the template. Click on ‘Manage’ in the Template Editor to bring up the window shown in Figure 54. Each available test has a name which appears in the window at the left. The minimum required information is:

• Position of the red lead (e.g. H1, A or N)

• Position of the black lead (e.g. X0, n or v) together these values are used to give the name of the test.

Figure 54 Managing Tests in a Template

A new test may be added by clicking on ‘New’ in the left hand side of the window. This adds a new entry to the template, as shown in Figure 55.

Figure 55 Adding a New Test to a Template Clicking on its entry in the window at left and then clicking on ‘Delete’ may delete a test. A dialog box appears to confirm deletion of the test, as shown in Figure 56.


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Figure 56 Deleting a Test from a Template

6.8.5. Deleting a Template To delete a template, click on the entry in the list of templates and then click delete. A dialog box appears asking for confirmation of the deletion, as shown in Figure 57.

Figure 57 Deleting a Template

6.8.6. Template Files The Doble SFRA Software comes complete with a set of preconfigured templates. These are in the Settings file of the directory where the data files are stored, as set up on installation. These files may be edited directly or replaced. Note: it is recommended that data is backed up before replacing a file.


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6.8.7. Importing a Set of Templates Further templates may be imported using a simple procedure to merge template files, as outlined for transformer file merge in section 6.14.

6.8.8. Associating a Template with a Transformer Templates may be created without reference to individual transformers entered through the Transformer Editor (see Section Error! Reference source not found.). To associate a template with a transformer, enter the Transformer Editor and click on the Test template tab, as shown in Figure 58.

Figure 58 Associating a Template with a Transformer Click Select to choose a template from the list of available templates.

6.9. Data Management Data Management with the Doble SFRA software is a simple but powerful process based on manipulating Windows ™ files. Data folders may be set up based on transformers, sub-stations, manufacturers or whatever the user decides. A default folder is set up for results. When a measurement is made, the resulting


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trace is saved to the default folder automatically. Traces are date and time stamped and may be moved or copied between folders as with any Windows ™ file.

6.9.1. Data Source The Data Source is the location for data: this can be any drive accessible by the software. Click on ‘Options’ under the Edit menu, as shown in Figure 59.

Figure 59 Options Menu The Dialog Box in Figure 60 appears. This gives the current locations for:

• Data Path • Editor List

Figure 60 Data Sources By clicking on the buttons marked ‘…’ a new dialog Box appears allowing selection of location, as shown in Figure 61.


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Figure 61 Selecting Data Source Location

6.9.2. Data Manager The Data Manager is accessed via the Data Manager tab on the main window, as shown in Figure 62. Results are show in spreadsheet form. Selecting one or more spreadsheet rows allows one or more traces to be selected for display.

Figure 62 Opening the Data Manager


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6.9.3. Selecting a Data Source Click on ‘Select Data Source’ to bring up a standard Windows Explorer ™ type window; this allows for selection of the folder where results are stored, as shown in Figure 65.

Figure 63 Selecting Data Source Note there is no ‘Delete’ option in the Doble SFRA software: to delete files, locate the file via the date and time stamp in the folder where it is stored and use Windows Explorer ™ to delete it. The automatic saving and procedure for deletion of files is set up to help protect data from inadvertent replacement or loss. By checking the box ‘Search All Sub-Folders’, results in any folders which are within the selected data source will also be displayed in the results spreadsheet.Click on ‘Set Data Source as Default’ to set the current data source as default for opening when the software is next run, as shown in Figure 64.

Figure 64 Confirmation of Data Source Being set as Default

6.9.4. Refresh Data Tree This function is only required when a new data source has been selected or additional SFRA traces have been made and stored in the default folder. They do not automatically appear in the data spreadsheet: a Refresh Data Tree click means that the traces will appear in the spreadsheet.

6.9.5. Displaying Traces (Results) The Data Manager lists all results that are saved to the current data source location. Figure 65 shows results stored in a particular folder. The actual list of results may be very long as each trace is identified separately. The directory-like tree structure on the right allows for selection of a subset of results for display.


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Figure 65 Available Results

6.9.6. Selecting a Subset of Results for Display To select a sub-set of results, use the ‘+’ sign next to a given attribute in the Tree to identify results. In Figure 66 we have:

• Looked at available Test Dates

• Selected for spreadsheet view only results from one test date as shown in the window to the right.

Figure 66 Selecting Results by Directory Tree


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To display a single result, click on the button at the left end of the result, as shown in Figure 67, then click on ‘Display Traces’.

Figure 67 Selecting a Single Result for Display To select multiple results, use the ‘Ctrl’ key and select entries by clicking on the gray buttons at the end of each test, as shown in Figure 68. Then click on ‘Display Traces’.

Figure 68 Highlighting Results for Display


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6.9.7. Exporting Results to a CSV file Having selected a sub-set of results, click on “Export Selected Results to CSV Files”. A dialog box appears as in Figure 69. Select a folder where the CSV files will be saved. There will be one CSV file for each measurement traces selected.

Figure 69 Choosing a Folder for CSV Export Having selected a folder, click “OK” and each measurement trace will be saved as CSV format in the folder, as shown in Figure 70. The source data is not affected.

Figure 70 Saving File in CSV Confirmation

6.9.8. Importing Location and Transformer from Results Files Having selected a sub-set of results, it is possible to add the Location and Transformer entries in each file to your own settings file. Click on “Import Location and Transformer From Results File”. If a Transformer or Location is imported, a confirmatory message is given, as shown in


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Figure 71 Confirmation of Transformer Import If no import is made, a message is shown, as in .

Figure 72 Confirmation of no Location Imports


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6.10. Importing 1.x and 2.x M5100 SFRA Files It is possible to import data from M5100 versions 1.x and 2.x software simply by placing those files in the appropriate data source location. See Section 6.9.1. Any M5100 files of version 1.x or 2.x will be parsed for content and put into the new Doble SFRA format. They will then be renamed with a different extension so as not to be re-converted subsequently. Make sure to have backed up copies of files imported as a precaution against loss of data. Nameplate data in M5100 versions 1.x and 2.x format is not easily converted to M5200/M5300 format. There are a number of corresponding fields, such as ‘Transformer Serial Number’ and ‘Location’ but location of test lead may be less obvious. All data imported should be checked for accuracy and details, with no ‘odd’ characters in any field, such as @, *,? etc..


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6.11. Running a Test

A test may only be performed using the M5300 or with a PC connected to an M5200 test set; it is not possible to perform a test from the PC Viewer version of the software without an instrment. Selecting a combination of performs a test:

• Transformer (complete with template) • Location • Test Organization • Test Equipment And then entering test Setup details. The software will not allow a test to be run without this combination of information.

6.11.1. Select Apparatus Click on ‘Select Apparatus’ from the Apparatus/Test Sub-pane to bring up a window similar to that in Figure 73. This window has sections for each element of data for the test to be selected.

Figure 73 Selecting a Transformer Location Combination


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Click on the transformer to be tested, the Location, the test Organization and the Test Equipment. This will give the combination of details, which will be tested; for review purposes a basic indication of selected details is given at the bottom of the ‘Apparatus and Test’ sub-pane, as shown in Figure 74.

6.11.2. Set Test Group Parameters Click on the ‘Apparatus and Test’ tab to bring up the Test sub-pane, as shown in Figure 74. This window allows general f parameters, which are valid for a group of successive tests on a transformer to be entered. A default set of test parameters are given:

• Oil – gives the level of oil in the transformer, defaults to full • Reason – is the motivation for the test, which is normally routine, the default value

Figure 74 Setting Test Parameters


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6.11.3. Select Test from Associated Template Having set test parameters for a group of tests, an individual test from a transformer template may be identified. Click on ‘Select test’ to bring up the window in Figure 75. Highlight the appropriate test and click OK.

Note: this does not start a test, and test details may still be edited before the test begins.

Figure 75 Choosing a Test from a Template

6.11.4. Start Test Click on ‘Start test’ or press ‘F2’ to start a test. The window shown in Figure 76 appears with values from the test template line selected filling the details fields.

Figure 76 Test Details


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As a minimum, it is necessary to fill in the location of the red test lead and the location of the black test lead. It is recommended to fill in as many test details as possible. This makes it more likely that the same test set up can be repeated in the future. The trace name is a combination of the Red and Black lead locations. If no test template was selected, a blank window is displayed, as shown in Figure 77. If the ‘Run test’ button is clicked without entering data, an error is recorded and the Lead Locations are highlighted, as shown in Figure 78.

Figure 77 Test Details if no Template was Used


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Figure 78 Red-Black Lead Locations are Required Fields


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6.11.5. Test in Progress When at least a minimum set of details has been entered, it is possible to run a test. Click on ‘Start Test’ in the test details window to return to the test sub-window, as shown in Figure 79.

Figure 79 Test in Progress At this point, the M5200 or M5300 will undergo a number of self tests to ensure:

• Internal Temperature does not exceed acceptable limits • Noise levels on the test leads do not exceed safe levels for the instrument • Resistance between ground connections is not too high • The internal M5200/M5300 performance check was successful

If each test is successful, as is usually the case, then no message is given and the test starts. If however, a test fails, then one of the following messages is given. The M5200 and M5300 are designed to operate in a 50oC environment for extended periods. The internal temperature is tested before each test as an elevated temperature may reduce component life and reduce reliability of the Doble SFRA instrument. If the temperature is abnormally high, a warning is given. It is possible to continue with the test, as shown in Figure 80, but it is recommended that the unit be switched off for a number of minutes to allow it to cool down first.


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Figure 80 Self Test - Temperature Excessive noise on the input channels may cause excessive noise in the results. If this level rises too high, it may damage the instrument. Consequently, the Doble SFRA instrument tests the noise level on the input channels, as shown in Figure 81, before each test. It is recommended that if a high noise level is found that the test is stopped, bushing terminals are grounded to reduce static, and the test restarted. It is possible to continue with the test, but results may be noisy.

Figure 81 Self Test – Noise An SFRA test is reliant on good test connections at the bushing terminal and at the base of the bushing. The Doble SFRA instrument tests the ground loop resistance before running a test, as shown in Figure 82. A value of less than 1 ohm is ideal, but less than 5 ohms is usually acceptable. Causes of high ground loop resistance include poor connections to bushing studs due to dirt, grease or paint or, occasionally, the stud itself not being grounded. Any measurement above 250 ohms should be considered an open circuit.

Figure 82 Self Test – Ground Continuity The Doble SFRA test set also generates signals at a number of frequencies and measures those without sending them through the test object; this signal verification test, as shown in Figure 83,


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confirms that the test set is performing as expected. If the test fails, it is still possible to continue with the SFRA measurement, but results should be checked for acceptability.

Figure 83 Self Test – Signal Generation

The test will have its progress monitored by a percent completion indicator and a value for the current frequency being tested.

6.11.6. Checking Results and Trouble Shooting Results SFRA is an easy test to perform, but experience has shown that some simple problems may occur during a test. These have a characteristic signature, discussed here.


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Monitoring Waveforms It is a feature of the Doble SFRA test sets to be able to monitor the reference and measured waveforms as we run through a test. Click on the ‘Waveform’ tab to display the waveforms, as shown in Figure 84.

Figure 84 Waveforms Both waveforms should be displayed. At very low dB response the measured waveform may be very small.


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Diagnosing Open Circuit Response An open circuit response may be caused by the black test lead dropping off the bushing, a poor connection or damage within the test lead. The blue trace in Figure 85 shows the typical open circuit response – about -100 to -115 dB. This test should be investigated – to check whether the open circuit lies in the test set up or in the transformer.

Figure 85 Typical Open Circuit Response


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Diagnosing Open Circuit in Red Test Lead The Doble SFRA test set monitors the output signal as a reference waveform. If this waveform is not present then an error is indicated, as shown in Figure 86 and Figure 87. This situation may be caused by forgetting to attach the test leads (not uncommon), a damaged test connection at the test set or possibly a damaged lead. This situation has also been caused by misconnecting the test leads such the red signal lead is grounded and no reference waveform is measured.

Figure 86 Open Circuit in Red Test Lead

Figure 87 Open Circuit in Test Lead Dialog Box


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6.12. Saving and Deleting Traces

6.12.1. Saving Traces All completed traces are automatically saved. If the test is canceled, the data is not saved.

6.12.2. Deleting Traces This is done through Windows Explorer. Individual files may be identified through a combination of:

• Manufacturer • Serial Number • Location • Date • Time It should be noted that each tabbed option in the data manager, which shows the traces, also gives the individual file name as the last field.

6.13. Transferring Data between Machines or PC’s This is easy to do using Windows Explorer. Identify tests to transfer and copy them to a disk or suitable medium. Transfer them to target PC by copying them to the location identified in the data source. The files will be then available through the Data Manager. The software will try to identify duplicate files but is not foolproof. Please be careful when copying and importing data.


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6.14. Merging Settings Files

Make sure all data and settings files are backed up before performing a merge operation. Settings files contain entered data for:

• Transformers • Locations • Test Organizations • Test Equipment • Test Templates The files are in XML format and can be found in the ‘Data Source’ directory under ‘Options’ on the ‘Edit’ menu – see Section 6.4.2. The method for merging Transformer Settings files described here is also applicable to other settings files. Care must be taken as incorrect merging could make the software unstable.

6.14.1. Opening a Settings File To open a settings file, use a standard text editor such as Microsoft Notepad. Microsoft Word should be avoided since it will attempt to save files in its native format, which is not compatible with the SFRA software. This document assumes the use of Notepad.

The following simplified view of the Transformer settings file will be used to describe the file in detail. Line # XML File 1 <?xml version="1.0" encoding="utf-8"?> 2 <transformerNameplates> 3 <transformerNameplate version="1"> 4 <manufacturer>ABB</manufacturer> 5 <serialNumber>1234</serialNumber> - . - . - . 54 </transformerNameplate> 55 <transformerNameplate version="1"> 56 <manufacturer>GE</manufacturer> 57 <serialNumber>xyz</serialNumber> - . - . - . 106 </transformerNameplate> 107 </transformerNameplates> Table 1 Transformer Settings XML Format


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Line 1 of the xml file is always the xml declaration that describes the xml version and encoding used. This must not be modified. Line 2 contains start tag that is the beginning of the container of all transformers contained in the file. It must have a matching end tag, which is shown on line 107. Line 3 contains the start tag of the first transformer nameplate and must also have an ending tag, shown on line 54 in this case. It is important to understand that the line numbers are only important for this example that describes the file contents, they may vary for different Transformer Settings files. Future versions may add or remove data that would shift absolute line numbers. It is important to recognize the xml start and end tags for each section. Line 55 shows the start another transformer that ends on line 106. If another transformer were added, it would start after line 106 on line 107, but it would be inserted before the xml tag </transformerNameplates> that is currently on line 107.

6.14.2. A Merge Example In this example we look at two SFRA users who wish to share XML files. Table 2 shows a simplified transformer settings file from User A (as viewed in Notepad): <?xml version="1.0" encoding="utf-8"?> <transformerNameplates> <transformerNameplate version="1"> <manufacturer>ABB</manufacturer> <serialNumber>1234</serialNumber> </transformerNameplate> <transformerNameplate version="1"> <manufacturer>GE</manufacturer> <serialNumber>xyz</serialNumber> </transformerNameplate> </transformerNameplates> Table 2 User A Transformer Settings XML File Table 3 shows another simplified transformer settings file from User B: <?xml version="1.0" encoding="utf-8"?> <transformerNameplates> <transformerNameplate version="1"> <manufacturer>ACME</manufacturer> <serialNumber>9999</serialNumber> </transformerNameplate> </transformerNameplates> Table 3 User B Transformer Settings XML File


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User A’s file contains two transformers (both underlined in the tables for clarity):

• ABB with serial number 1234 • GE with serial number xyz User B’s file contains one transformer:

• ACME with serial number 9999 The safest method for merging files is to combine the contents of the two files into a new file, which contains elements from both source files. The following procedure merges the contents into a new transformer Settings file. It makes use of the fact that several versions of Microsoft’s Notepad ™ may be run simultaneously.

• Back up all TransformerList.xml files. • Start a version of Notepad and load User A’s TransformerList.xml file. • Start another version of Notepad and load User B’s TransformerList.xml file. • Start another Notepad; we will merge original data into this blank Notepad document. • Select the entire text in User A’s file and paste it into the blank Notepad. Close User A’s file. • Select just the transformerNameplate section from User B’s file, as shown in Table 4:

<transformerNameplate version="1"> <manufacturer>ACME</manufacturer> <serialNumber>9999</serialNumber> </transformerNameplate>

Table 4 Transformer Nameplate Section from User B File

• Close User B’s file. • In the remaining notepad, place the cursor on the beginning of Line 3 and paste the text. This

will incorporate the transformer nameplate that was copied. Check that the file has the right format – carriage returns and line feeds to ensure readability of the document

• Save the file as TransformerList.xml. • You can now overwrite the existing TransformerList.xml file located at My

Documents\SweepFrequencyResponseAnalyzer\Settings (or wherever the Data Source has been configured to address) with this file either by saving to this location or copying the file using Windows Explorer.

6.14.3. Merging Caveats The manual merge is prone to cut and paste errors. It will be updated in a future version of the SFRA software. Be especially careful to avoid possible duplicate entries in any Settings file; this may cause the SFRA software to become unstable. Back up all files before merging.


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6.15. Application Details

6.15.1. Graph Options The Graph Menu, shown in Figure 88, allows control of various aspects of the display area.

Figure 88 Graph Options Menu Most of the controls are intuitive; a short description is given here.

Cursor 1 Click on ‘Cursor 1’ to display the blue cursor. Current cursor co-ordinates are displayed in a field at the bottom of the graph, as shown in Figure 89. The cursor will ‘attach’ itself to a trace. By moving the mouse pointer over the cursor lines it is possible to move it around the graph. The cursor will always attach itself to the nearest graph.

Figure 89 Clicking on Cursor 1


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Cursor 2 Click on ‘Cursor 2’ on the Graph menu to bring up Cursor 2, which is displayed in red, as shown by the co-ordinates at the bottom of the graph, in Figure 90.

Figure 90 Two Cursors Displayed – Red and Blue

Center Cursors By clicking on ‘Center Cursors’ the cursors are taken to the center of the displayed graph. This is the center of the scale values – which may be offset on a log scale, as shown in Figure 91.

Figure 91 Centered Cursors


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Zoom On a log or linear scale, the zoom function works by zooming in between cursor positions. Both cursors must be visible. On a linear scale it is possible to zoom in on a particular area by holding down the shift key then using left click drag and drop.

Unzoom Clicking on ‘Unzoom’ on the Graph menu resets the graph to default values.

New Range Clicking on ‘New Range’ brings up the Dialog Box shown in Figure 92. This allows for manual setting of the plot maxima and minima. This is useful when producing zoomed plots of set graph areas for reports.

Figure 92 Plot Range Dialog Box Click on ‘Restore Defaults’ to reset all values to their original level.


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Log & Linear Options

Click on ‘Log’ or ‘Linear’ on the ‘Graph option to set the X-axis scale mode for the graph. Figure 93 and Figure 94 show the same graph on Log and Linear scales. The Log scale allows for display of all data in one chart emphasizing lower frequencies. The Linear scale also displays all data but emphasizes higher frequencies.

Figure 93 Graph using Default Log Scale


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Figure 94 Graph with Linear Scale

Clear Traces Click on ‘Clear Traces’ on the Graph menu to bring up the dialog box shown in Figure 95. Check one or more traces for deletion from the display. Note this is different to checking the boxes on the legend display, which makes an individual trace visible or invisible.

Figure 95 Clear Traces Dialog Box


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6.15.2. Pan On the graph screen hold down the ‘control’ key and use the left mouse button to drag the traces across the screen.

6.15.3. Analyze The ‘Analysis’ tab brings up the display in Figure 96.

Figure 96 Analysis Display


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Click on ‘Select Traces’ to bring up the Dialog Box in Figure 97.

Figure 97 Analysis - Select Traces Dialog Box This Dialog box allows the user to select two traces for analysis using difference and correlation. If less than or more than two traces are selected, the dialog box in Figure 98 is displayed, and no action is taken.

Figure 98 Incorrect Number of Traces Selected


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Having selected two traces, the results are shown, as in Figure 99.

Figure 99 Analysis of Two Traces The Analysis screen allows analysis of two traces for the overlapping section of the two traces. For instance, if one trace is 10 Hz to 2 MHz and the other 20 Hz to 10 MHz, the analysis will cover 20 Hz to 2 MHz, the higher of the lower values to the lower of the higher values. This is where the two traces ‘overlap'.

Difference Analysis The difference plot shows a trace of the difference between the two plots using the user selected dB limits to color the result. Figure 100 shows the section of the display where these values are set.

Figure 100 User Defined Difference Limits


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A difference of less than 2.0 dB will be plotted on the difference chart in green; a difference between 2.0 dB and 5.0 dB will be plotted in yellow, while a difference of more than 5.0 dB will be plotted in red. The display shows the results of these values, as shown in Figure 101.

Figure 101 Difference Plot Selecting new values for the difference plot, as shown in Figure 102, results in a new difference chart, as shown in Figure 103, when the ‘Recalculate button on the display is clicked.

Figure 102 Edited Difference Plot Values

Figure 103 Difference Plot with New Limits

Correlation Analysis Correlation analysis between two traces is performed on sub-sections of the two traces. Figure 104 shows the default bands.

Figure 104 Correlation Range Display The cursor positions for the correlation bands are set by either moving the cursors or by altering the corresponding field values, as shown in Figure 105. The cursor colors correspond to the field backgrounds in Figure 105.


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Figure 105 Correlation Range Selections

The value of the correlation coefficient in each range is given in the fields below the cursor selection, as shown in Figure 106.

Figure 106 Correlation Coefficients

If the cursors are moved, the values of the correlation coefficients must be recalculated using the ‘Calculate’ button on the screen. The correlation coefficient limits are set by the fields on the ‘Analysis’ tab shown in Figure 107. These values govern the values of the correlation coefficient results.

Figure 107 Correlation Limits After editing the correlation limit values, or amending the cursor positions, click on ‘Recalculate’ to determine the new correlation values.

Analysis Discussion There are no standard limits for acceptability of SFRA traces. Doble is involved in the latest research and submissions to International Standards Organizations such as IEEE and CIGRE. Recommendations from these organizations along with Doble proprietary experience will be incorporated into the Doble Expert System for SFRA Analysis: SAM™ (SFRA Analysis Manager).


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6.15.4. Printing and Reporting Click on the ‘File’ menu to display the menu shown in Figure 108.

Figure 108 File Menu – Print and Print Preview Print Preview brings up the Dialog Box shown in Figure 109. This Dialog Box allows for preview of the printed report.

Figure 109 Print Preview Dialog Box The report consists of two parts: The graph area – showing those traces on the graph, which are checked (and thus displayed) The details pages – showing test details for each trace, as shown in Figure 110.


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Figure 110 Print Preview Details Page


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Clicking on ‘Print’ from the ‘File’ menu to bring up the standard Windows print Dialog Box, as shown in Figure 111.

Figure 111 Windows Print Dialog Box

6.16. Closing the Software When closing down the Doble SFRA software a window will appear confirming that you wish to exit the software, as shown in Figure 112

Figure 112 Exit Software Confirmation If you click ‘yes’ a reminder window appears, Figure 113, asking for a computer restart before restoring connections to any networks.


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Figure 113 Actions before Restoring Network Connections


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Chapter 7 Application – Connections Generally, an SFRA measurement is made from one terminal on the transformer (e.g H1 or A) to another terminal (e.g. H2 or N). It is important to record all relevant information, which includes tap position, oil level and terminals grounded or shorted. It is IMPORTANT to note that where previous test results exist, the best testing procedure is to repeat those tests: taking note of tap position, shorted or grounded bushings and any particular details for specific tests performed. Doble is a key member of international bodies such as CIGRE and IEEE, which are pursuing FRA test standards. As standards develop, recommended tests may be changed with input from experienced users around the world. Doble will reflect those changes.

7.1. Measurement Types

7.1.1. Open Circuit An open circuit measurement is made from one end of a winding to another with all other terminals floating. For a delta winding, connections would be H1 to H3, for example. For a star (wye) winding measurements are taken from HV terminals to neutral, such as X1 to X0.

7.1.2. Interwinding An interwinding measurement is from one from one winding to another with all other terminals floating. This would include, for example, H1 to X1 on a double wound transformer or H1 to Y1 on an autotransformer with a tertiary. Note that H1 to X1 on an autotransformer is not an interwinding measurement but an open circuit measurement on the series winding. Interwinding measurements are usually considered as optional tests or tests for further investigation when open circuit and short circuit tests are inconclusive.


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7.1.3. Short Circuit A short circuit measurement is made with the same SFRA test lead connections as an open circuit measurement but with the difference that another winding is short circuited. To ensure repeatability, Doble recommends that the three voltage terminals on the shorted winding are all shorted together. This would mean, for example, shorting X1 to X2, X2 to X3 and X3 to X1. This ensures all three phases are similarly shorted to give a consistent impedance. Any neutral connections available for the shorted winding should not be included in the shorting process.

7.2. Test Templates The test templates given here do not indicate tap changer position or no-load tap changer position. There are two test categories: comprehensive and basic. A comprehensive set of tests would make measurements at both neutral position and an extreme tap position, such as extreme raise. A comprehensive set of measurements includes open circuit, short circuit and interwinding measurements. A basic set of tests, recorded when a baseline is needed and there is no question of the transformer’s health and time is short, consists of a set of results only taken at extreme tap position. A basic set of measurements includes open circuit and short circuit measurements only.

Note Interwinding tests are marked with an asterisk to indicate their optional nature.

Note Each table gives the recommended tests with position of the red lead and black lead clearly identified. Reversing these test leads may provide small variations in higher frequency response. Care must therefore be taken in attaching test leads in the appropriate manner.

Note on LTC Position

Changing LTC will change SFRA response; LTC position should be recorded. At neutral tap, previous tap position should also be recorded.

Note on DETC Position

Transformers in service occasionally have problems due to DETC movement; it is not recommended that DETC position be altered for an SFRA test. The exception is in factory tests on a new transformer where it can be assumed that the DETC is in operating condition, and tests performed on nominal tap.

Note on Grounding Connections Good grounds are key to good high frequency responses – make sure ground connections are not hampered by loose connections, paint or dirt and grease.


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7.3. Two Winding Transformers

Test Type Test # 3φ Delta-Wye

3φ Wye- Delta

3φ Delta-Delta

3φ Wye-Wye 1φ

Test 1 H1-H3 H1-H0 H1-H3 H1-H0 Test 2 H2-H1 H2-H0 H2-H1 H2-H0

HV Open Circuit (OC) All Other Terminals Floating Test 3 H3-H2 H3-H0 H3-H2 H3-H0

H1-H2 (H1-H0)

Test 4 X1-X0 X1-X3 X1-X3 X1-X0 Test 5 X2-X0 X2-X1 X2-X1 X2-X0

LV Open Circuit (OC) All Other Terminals Floating Test 6 X3-X0 X3-X2 X3-X2 X3-X0

X1-X2 (X1-X0)


Short Circuit (SC) High (H) to Low (L) Short [X1-X2-X3] Test 9 H3-H2 H3-H0 H3-H2 H3-H0

H1-H0 Short [X1-X2]

Table 5 Two Winding Transformers

7.4. AutoTransformers

Test Type Test # 3φ 1φ Test 1 H1-X1 Test 2 H2-X2 Series Winding (OC)

All Other Terminals Floating Test 3 H3-X3

H1-X1

Test 4 X1-H0X0 Test 5 X2-H0X0 Common Winding (OC)

All Other Terminals Floating Test 6 X3-H0X0

X1-H0X0

Test 7 Y1-Y3 Test 8 Y2-Y1 Tertiary Winding (OC)

All Other Terminals Floating Test 9 Y3-Y2

Y1-Y2 (Y1-Y0)

Test 10 H1-H0X0 Test 11 H2-H0X0

Short Circuit (SC) High (H) to Low (L) Short [X1-X2-X3] Test 12 H3-H0X0

H1-H0X0 Short [X1-H0X0]

Test 13 H1-H0X0 Test 14 H2-H0X0

Short Circuit (SC) High (H) to Tertiary (Y) Short [Y1-Y2-Y3] Test 15 H3-H0X0

H1-H0X0 Short [Y1-Y2]

Test 16 X1-H0X0 Test 17 X2-H0X0

Short Circuit (SC) Low (L) to Tertiary (Y) Short [Y1-Y2-Y3] Test 18 X3-H0X0

X1-H0X0 Short [Y1-Y2]

Table 6 Autotransformers


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7.5. Three Winding Transformers

Test Type Test # 3φ Delta-Delta-Delta

3φ Delta-Delta-Wye

3φ Delta-Wye-Delta

3φ Delta-Wye-Wye 1φ

Test 1 H1-H3 H1-H3 H1-H3 H1-H3 Test 2 H2-H1 H2-H1 H2-H1 H2-H1 HV Open Circuit (OC)

All Other Terminals Floating Test 3 H3-H2 H3-H2 H3-H2 H3-H2

H1-H2 (H1-H0)

Test 4 X1-X3 X1-X3 X1-X0 X1-X0 Test 5 X2-X1 X2-X1 X2-X0 X2-X0 LV Open Circuit (OC)

All Other Terminals Floating Test 6 X3-X2 X3-X2 X3-X0 X3-X0

X1-X2 (X1-X0)

Test 7 Y1-Y3 Y1-Y0 Y1-Y3 Y1-Y0 Test 8 Y2-Y1 Y2-Y0 Y2-Y1 Y2-Y0 Tert Open Circuit (OC)

All Other Terminals Floating Test 9 Y3-Y2 Y3-Y0 Y3-Y2 Y3-Y0

Y1-Y2 (Y1-Y0)


Short Circuit (SC) High (H) to Low (L) Short [X1-X2-X3]* Test 12 H3-H2 H3-H2 H3-H2 H3-H2

H1-H0 Short [X1- 2]*


Short Circuit (SC) High (H) to Tertiary (T) Short [Y1-Y2-Y3]* Test 15 H3-H2 H3-H2 H3-H2 H3-H2

H1-H0 Short [Y1-2]*

Test 16 X1-X3 X1-X3 X1-X0 X1-X0 Test 17 X2-X1 X2-X1 X2-X0 X2-X0

Short Circuit (SC) Low (L) to Tertiary (T) Short [Y1-Y2-Y3]* Test 18 X3-X2 X3-X2 X3-X0 X3-X0

X1-X0 Short [Y1-2]*

Table 7 Three Winding Transformers – Part 1

Test Type Test #

3φ Wye-Wye-Wye

3φ Wye-Wye-Delta

3φ Wye-Delta-Wye

3φ Wye-Delta-Delta

Test 1 H1-H0 H1-H0 H1-H0 H1-H0 Test 2 H2-H0 H2-H0 H2-H0 H2-H0 HV Open Circuit (OC)

All Other Terminals Floating Test 3 H3-H0 H3-H0 H3-H0 H3-H0 Test 4 X1-X0 X1-X0 X1-X3 X1-X3 Test 5 X2-X0 X2-X0 X2-X1 X2-X1 LV Open Circuit (OC)

All Other Terminals Floating Test 6 X3-X0 X3-X0 X3-X2 X3-X2 Test 7 Y1-Y0 Y1-Y3 Y1-Y0 Y1-Y3 Test 8 Y2-Y0 Y2-Y1 Y2-Y0 Y2-Y1 Tert Open Circuit (OC)

All Other Terminals Floating Test 9 Y3-Y0 Y3-Y2 Y3-Y0 Y3-Y2 Test 10

H1-H0 H1-H0 H1-H0 H1-H0

Test 11

H2-H0 H2-H0 H2-H0 H2-H0 Short Circuit (SC) High (H) to Low (L) Short [X1-X2-X3]*

Test 12

H3-H0 H3-H0 H3-H0 H3-H0

Test 13

H1-H0 H1-H0 H1-H0 H1-H0

Test 14

H2-H0 H2-H0 H2-H0 H2-H0 Short Circuit (SC) High (H) to Tertiary (T) Short [Y1-Y2-Y3]*

Test 15

H3-H0 H3-H0 H3-H0 H3-H0

Test 16

X1-X0 X1-X0 X1-X3 X1-X3

Test 17

X2-X0 X2-X0 X2-X1 X2-X1 Short Circuit (SC) Low (L) to Tertiary (T) Short [Y1-Y2-Y3]*

Test 18

X3-X0 X3-X0 X3-X2 X3-X2

Table 8 Three Winding Transformers – Part 2


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Chapter 8 Examples

In this section we give typical results from a number of different transformer windings and designs. They are given here as typical examples of how results vary between transformers – both designs and phases.

8.1. Three Responses for One Transformer Figure 114 shows the two open circuit responses and the short circuit response of one phase of an autotransformer. The three traces are clearly quite different at low frequencies.

The HV response starts at a much lower level, about –50 dB than the LV response which is at about –22 dB. The short circuit response is approaching 0 dB at low frequency but comes back in line with the HV response at higher frequencies.

Figure 114 Responses for One Phase of a Transformer


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8.2. HV Delta Response

Figure 115 shows the responses for three phases of a HV delta winding. This is a characteristic response at low frequencies:

• The center phase has a slightly higher impedance (more negative response) at lower frequencies

• The center phase is different to the outer phases at the first resonance below 10 kHz • The center phase is more similar to the outer phases as we rise in frequency • All three phases have the same basic shape above about 100 kHz

Figure 115 HV Delta Winding Responses


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8.3. HV Wye (star) Response

Figure 116 shows a typical HV wye (star) winding response. All three phases show similar responses at low frequencies, with the following characteristics:

• The center phase has a slightly increased impedance (more negative dBs) at low frequencies

• The center phase has one resonance and the outer phases two resonance below about 1 kHz • The outer phases are very similar at low frequencies • The three phases ‘come back together’ as frequencies rise toward 10 kHz • The three phases show regions of similarity and regions of dissimilarity across the

frequency range

Figure 116 HV Wye Winding Response


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8.4. Short Circuit Test Response

Figure 117 shows the three short circuit responses from the HV side of a transformer. Clearly the responses are very similar, which is what we would expect from this test.

Figure 117 Short Circuit Test Response Even when we zoom in on the responses, as shown in Figure 118, they are still very similar. This is a useful diagnostic where no previous results are available.

Figure 118 Short Circuit Response – Detail


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8.5. Repeat Results for One Phase at Different Times

The two responses shown in Figure 119 were taken 18 months apart; the original data was taken as a baseline set of results; the subsequent data was taken after an incident involving the transformer.

Figure 119 Repeat Results for One Phase The results are very similar. Low frequency variation, below about 5 kHz, is characteristic of core magnetism affecting the results; the traces have the same basic shape but one is offset compared to the other; they come back into lone as we approach 10 kHz. The higher frequency results are almost identical; this is strong evidence that there has been no change within this transformer.

8.6. Results Showing a Shorted Turn A shorted turn produces a similar effect to shorting the low side windings for a short circuit measurement. The effect is very easy to see at low frequencies, and does not require reference results. The original results show the characteristic low frequency response of a wye (star) winding. The subsequent results, taken a year later after a close in fault, show the characteristic response of a short somewhere on that phase.


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Figure 120 Shorted Turn on one Winding


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Chapter 9 Data Interpretation

9.1. Frequency-dependant Transformer Equivalent Circuit The power transformer equivalent circuit is a very complicated network of distributed resistive, capacitive and inductive elements. These include: • Capacitance between the neighboring turns of the same winding. • Capacitance between the turns of different windings. • Capacitance between the turns and the ground. • Turns self-inductance. • Turns mutual inductance. • Conductor dc resistance. • Resistance that accounts for dielectric losses in insulation. • Resistance that accounts for eddy losses in conducting and magnetic components. Depending on the test leads connection, the equivalent circuit involved in the measurement represents an individual phase of the winding, the space between phases in a given winding or the space between the windings. Size of the conductors, diameters of the coils, distance between the coils, distance between the windings, number of turns, type of the core, winding configuration, type and thickness of insulation, geometry and size of supporting material are among the factors that define the elements of the equivalent circuit. Furthermore, each element is specific to the transformer design and even influenced by the ability of the manufacturing shop to replicate the units of the same design. Therefore, there is a direct relationship between the geometry of core-winding configuration and the network of distributed resistive, capacitive and inductive elements. Since reactance of capacitive and inductive elements is frequency dependent, the contribution of each element to the overall network impedance varies with frequency making the equivalent circuit unique at each frequency. Therefore, the signature that represents the changing continuum of the network impedance with frequency uniquely describes the geometry of the core-winding configuration for a given unit and carries a wealth of diagnostic information. The network impedance, which is the ratio of the output and input signals, is often referred to as the transfer function. The frequency response analysis (SFRA) uses the transfer function behavior over the specified range of frequencies as the transformer diagnostic signature. Being a complex variable, the transfer function is described by the magnitude and the phase angle.


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9.2. Diagnostic Significance of Frequency Ranges

Diagnostics of frequency ranges are discussed on two levels:

• Per-phase Open Circuit Measurement • Short Circuit Measurement

9.2.1. Per-phase Open Circuit Measurement As the name implies, the per-phase measurement targets the individual phase of a given winding. At low frequencies, the influence of capacitance is negligible and the winding behaves as an inductor. Therefore, the attenuation (described by the magnitude of the transfer function) and the phase shift (described by the phase of the transfer function) of the low-frequency sinusoidal signals, passing through the winding, are determined by inductive and resistive nature of the network. The inductive characteristics are determined by the magnetic circuit of the core and the resistive characteristics are dominated by the resistance of the output measuring cable. An example of transfer function magnitude and phase for a per-phase measurement is shown in Figure 121 and Figure 122. In Figure 122 the phase angle is around −80 degrees, indicating the inductive nature of the total impedance (in the region below 1 kHz). For a three-legged core-type unit, the magnetic flux coupled with the outer phase (H1-H3 or H3-H2 in Figure 121) faces a different reluctance than the flux coupled with the middle phase (H2-H1 in Figure 121). Therefore, the corresponding magnitude traces, in the low frequency range, differ as well, i.e., the traces for the two outer phases correlate very closely and are shifted from the middle-phase trace. The presence of the residual magnetism may have an effect on relationship between the traces. This is the same phenomenon that, during exciting current and loss measurement, creates a pattern of two high similar and one lower reading under normal conditions and a slightly distorted pattern in the presence of residual magnetism.

Figure 121 Per-Phase Measurement –Magnitude of the Transfer Function


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Figure 122 Per-Phase Measurement – Phase of the Transfer Function As the frequency of the input signal increases, the capacitive effects begin to dominate and the phase angle quickly becomes close to +90 degrees (in the region above 1 kHz). Now, the attenuation and the phase shift of the high-frequency sinusoidal signals, passing through the winding, are determined by inductive and capacitive nature of the network. However, in high-frequency region, the inductive characteristics are determined by the leakage flux coupling and the capacitive characteristics are determined by the various capacitance elements associated with individual turns. The propagation characteristic of the winding becomes complex as a result of the many resonance frequencies found in the high-frequency range. However, since the winding responses become less dependent on the magnetic circuit of the core, the traces of the three phases converge and become quite similar. As the frequency increases even further (over 100 kHz in Figure 122), the sinusoidal signals travel mostly outside the winding and reflect the other elements found in the transformer, e.g., leads, support insulation, etc. The magnitude and the phase of the transfer function in that frequency region are influenced by the inductive-capacitive-resistive nature of these elements. Although most of the low-frequency magnitude responses exhibit a typical shape, there are no typical form responses in the high-frequency region. These vary greatly with design of the unit. Therefore, the frequency ranges noted in description of Figure 121 and Figure 122, are different for different units.


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9.2.2. Short Circuit Measurement The aim of this measurement is to allow direct comparison between the three phases of a three-phase transformer where no prior measurements exist. By making a measurement on one winding with another winding short circuited, the effect of the core at low frequencies is removed. The resulting response is that for a large inductor with no core. The responses for all three phases should be very similar at low frequencies. The theory behind the short-circuit measurement is straightforward. Any two winding transformer may be modeled at low frequencies by a simple T-model, as shown in Figure 123.

R small

R high

R small

HV Winding LV Winding

Core

Signal & Reference

Test

M5100

Normal test on HVs - LVs float

Model is relevant for LOW FREQUENCIES Figure 123 T Model of Transformer Winding The impedance of the windings is small, while the impedance of the core to ground is extremely high. This means that for any input signal, the response is dominated by the core. By adding a short to the LV side, the effect of the core is removed and the response is dominated by the windings, which are predominantly inductors at low frequency. The response of an inductor is to have a low db response at low frequency with an inductive roll off as frequency rises, as shown in Figure 124.

R small

R high

R small

HV Winding LV Winding

Core

Signal & Reference

Test

M5100

Normal test on HVs - LVs float

Model is relevant for LOW FREQUENCIES Figure 124 T Model with LV Short

M5200/5300

M5200/5300


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All three phases of a transformer have similar winding inductances, which means their responses should be very similar. See Chapter 9 for examples of the use of the short circuit response for diagnostic purposes.

9.3. Analysis of Test Data Topics concerned with analysis of test data include:

• Initial Measurement • Subsequent Measurement • Other Diagnostic Measurements

9.3.1. Initial Measurement Present state of the art is such that analysis of SFRA data is based only on a subjective comparison of traces. For the initial measurement, the traces are analyzed for changes between responses of the three phases of the same transformer and changes between responses of transformers of the same design. Obviously, for the single-phase unit, only the later comparison is applicable. The appearance of new features or major resonance frequency shifts is a cause for concern. When tapped windings are involved, it is useful to perform measurements on at least two tap positions, to assess whether differences in the trace originate from the tapped or untapped sections of the winding. When interpreting differences observed between phases, bear in mind that for many windings there may be minor design differences associated with the disposition of internal connections between windings, bushings and tap-changers. These differences could introduce small differences between phases in the frequency response. Therefore, for the initial measurement, if minor differences between phases are observed, it is not possible to make an unambiguous conclusion about the presence of winding deformation. Fortunately, responses obtained for units of the same design can often serve as a reference data for each other. Short circuit measurements allow for direct phase-to-phase comparison of a three phase transformer.

9.3.2. Subsequent Measurement For the subsequent measurement, the traces are analyzed for changes between the initial and subsequent response. Considerations described for the initial measurement apply here as well. Any variation in response between an initial measurement and a subsequent measurement must be treated with caution. Low frequency variations usually relate to core effects, including residual magnetism, which may provide variation between responses. Higher frequencies, above 1 MHz, may well be affected by grounding quality; this is easy enough to identify but must be considered as a cause of variation.


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9.3.3. Other Diagnostic Measurements Each FRA diagnostic measurement has failure modes it is most sensitive to as its purpose in life. Therefore, understanding the significance of each measurement and knowing its associated failure modes is essential for a successful diagnostic investigation. Table 9 Diagnostic Tests relates the typical failure modes with various diagnostic measurements. This table also shows that no single method can cover the multitude of problems occurring in transformers. Failure Mechanism

Failure Mode Diagnostic Measurement

Windings Electromagnetic forces caused by overcurrent conditions change the geometry of the winding, and so changing the measured leakage reactance.

Winding distortion

FRA, leakage reactance

Windings Insulation failure creates a circuit coupled with the main flux. The resulting circulating current creates a load component in the measured exciting current and loss.

Turn-to-turn winding failure: a) One or more turns are short-circuited

completely. b) Two or more parallel

strands of different turns are short-circuited.

FRA, exciting current and loss, DGA

Windings Insulation failure creates a circuit coupled with the leakage flux. The resulting circulating current contributes a load component to the measured leakage loss.

Strands within the same turn are short-circuited.

Leakage loss, DGA

LTC contacts Contact problems affect the current circulating through the preventive autotransformer in bridging positions. The change in the circulating current influences the load components of the exciting current and the loss measured in the bridging positions.

Misalignment, Mechanical problems, coking and wear of LTC and DETC contacts.

Exciting current and loss, DGA


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Failure Mechanism

Failure Mode Diagnostic Measurement

DETC contacts Contact problems change the resistance of the current path.

Misalignment, Mechanical problems, coking and wear of LTC and DETC contacts.

DC winding resistance, DGA

Conductors Movement of conductors results in the breaking of strands and the deterioration of terminations changing the resistance of the current path.

Open circuit, broken strands, termination problems.

Exciting current and loss, DC Winding resistance, DGA.

Core Movement or over excitation of the magnetic system creates a circuit coupled with the main flux. The resulting circulating current contributes a load component to the measured exciting current and loss.

Overheating due to (abnormal) circulating currents in the core, clamping components and through multiple core grounds.

FRA, exciting current and loss

Moisture, aging, contaminants, poor maintenance, and manufacturing defects leads to insulation deterioration.

Dielectric breakdown of insulation.

Power factor and capacitance (including measurements on bushings), oil tests, DGA

Table 9 Diagnostic Tests


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Chapter 10 Application Notes

10.1. Short Circuit Lead Responses The Cable Continuity Test is performed next. It verifies the proper condition of the Test Specimen Cable, which is connected to the Doble SFRA Instrument and then short circuited by connecting alligator clamps. Since there is no attenuation, signal loss between the Source/Reference and Measure, the resulting data graph plots along the 0 dB horizontal line as frequency increases, until an inductive roll off occurs, as shown in Figure 125. This roll off is a feature of the cables due to the 12 feet (3.7m) ground connections. This roll off is consistent for all tests and reduces the variability in response due to variation in ground lead length. It is expected and acceptable.

Figure 125 Short Circuit Lead Response


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10.2. Open Circuit Lead Responses

The Open Circuit lead Test is performed next. It is performed for two reasons:

• To confirm that the Doble SFRA Instrument recognizes an open circuit condition for any or all of the connections of the Test Specimen Cable.

• To train the operator to recognize this condition and correct it, which results in more efficient and accurate accumulation of good SFRA test data.

Figure 126 shows the open circuit lead response which is also around 0 dB but is clearly affected by noise and shows a lot of ‘hashing’ compared to the short circuit lead response. It is relatively easy to identify.

Figure 126 Open Circuit Lead Response

10.3. Cable Length RG-58 50 Ohm impedance matched test leads are used. The SFRA measurement requires a matched impedance signal cable, and performs a single-ended measurement, i.e., the signal with respect to the instrument ground. Thus, the shield of the signal cable must be connected to the chassis via RF BCN connectors. Practical field experience dictates the leads be 60 ft. in length. This length has been selected as being the minimum length required to test the largest transformers from a location on the ground adjacent to the unit. Nevertheless, it is the lead length that determines the maximum effective frequency. At lengths of 60 ft., the cable approximates the wavelengths of the higher measurement frequencies, and there is probably little to be gained from the 2-10 MHz scan. As long as the cable is less than ¼ of a wavelength in length, the short cable approximation can be used. At lengths greater than ¼ of a wavelength, phasing effects start to occur. It turns out that at 60 ft., the frequency cutoff with respect to wavelength is approximately 2 MHz.


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It is important for the operator to not only recognize any problems with the cables, but to be prepared to confirm a problem further by, for example, having an ohmmeter available when a cable is recognized by the Doble SFRA Instrument as having an open circuit condition. The connections to the apparatus must be contaminant free, metal-to-metal junctions. This assures not only reliable and efficient SFRA data collection, but helps to reduce the effects of noise and interference inherent in a substation environment. Remember that a bad connection to the apparatus can appear as an open circuit cable.


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Chapter 11 Technical Support and Troubleshooting This section should help with most problems if you are having trouble with you Doble SFRA Test Set. In addition, you can always call Doble for support or e-mail [email protected].

11.1. PC The Doble M5200 test set requires the M5200 SFRA software running on a computer connected to the test set. The minimum PC specification is given in Table 10. Specification Requirement Processor 500 MHz Operating system Windows 2000, XP RAM 256 Mb Hard Drive Free Space 20 Mb for application Communications Ethernet crossover cable Table 10 Minimum PC Requirements

11.2. Installing Software on a PC The Doble SFRA software is loaded on your PC using standard software load procedures. As part of the load, the Microsoft.Net™ framework is installed on your machine if it is not already present. This will fail to load if there is insufficient disk space available. Do NOT install the software to a network drive or to an image of a network drive – these will not be available in the field and data will not save.

11.3. Running Your First Test There is a minimum set of data that must be entered by the user before a test can be run:

• A transformer nameplate complete with template selected • A location • M5200/M5300 Test Set Serial Number • Test Organization

If these are not entered the software will give an error message and ask for the data to be entered. See Section 0.

11.4. Checking Communication between PC and M5200 The user PC with M5200 software needs to be connected to the M5200 using a network cable and crossover adapter or a plain crossover cable. Use of a standard network cable without adapter will not allow communication and SFRA tests may not be made.

11.5. Field repairs There are no user maintainable parts within the M5200 or M5300. Contact Doble customer service at 617-926-4900 or e-mail [email protected] for support.


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In a case of a severe problem, your Doble technical support team may recommend removal of one the boards within the Doble SFRA test set for return to Doble. This is a simple process, but appropriate precautions should be taken to prevent electrostatic build up and discharge damage to the boards:

• Disconnect M5x00 from power supply • Remove power leads and test cables • Remove main cover of M5x00 • Disconnect power supply from input connector on front panel • Unscrew main circuit board assemblies, complete with power supplies

Before returning any defective modules to Doble, call or e-mail Customer Service to receive an RMA number. Return the main modules to Doble in padded and protective packaging.

11.6. Parts List Table 11 lists the parts you may obtain for the M5300 from Doble Engineering Company. LIST NUMBER PART NUMBER DESCRIPTION 1. (Figure 128) 03D-1632-01 Front Panel Assembly 2. (Figure 128) 380-0055 Fan 3. (Figure 128) 401-0292 CPU PC Board 4. (Figure 129) 384-0216 Power Supply +5V, +12V Output 5. (Figure 130) 03D-1633-01 CPU Module Assembly 6. (Figure 131) 045-0852-01 Assembly, PCB +15V Converter 7. (Figure 132) 401-0063 High Density Drive, 20GB IDE 8. (Figure 133) 03D-1631-01 PPC4/Analog Module Assembly 9. (Figure 134) 401-0295 USB Keyboard 10. 02C-0019-01 Cable, Ground, 30' M4K/M2H/MEU 11. 05B-0654-01 Ground. Jumper Extender 3 Ft. 12. 05B-0655-01 Ground. Jumper Extender 5 Ft. 13. 05B-0659-04 Cable, Specimen Test, M5200 14. 2FB-3449-01 Bag, Cable, Large 15. 401-0196 Software, Win XP, OEM Package 16. 071-0036-04 Cable Bag 17. (Chapter 13.) Littlefuse 312 001P Fast

Blo, 3AG Glass Cartridge UI and CSA certified or equivalent

M5200 Fuse

18. (Chapter 13.) Littlefuse 312 01.5P Fast Blo, 3AG Glass Cartridge UI and CSA certified or equivalent

M5300 Fuse

Table 11 Parts List


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Figure 127 Front View of M5300

Figure 128 Front Panel Assembly, CPU PC Board, and Fan

Ethernet

External

Upon power up, lights after measurement & PC boards have passed test. Specimen Connections

AC “ON” Light

USB

System OK Light

Fan

CPU PC Board

Front Panel Assembly


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Figure 129 Power Supply - +5V, + 12V Output

Figure 130 CPU Module Assembly


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Figure 131 Assembly, PCB + 15V Converter

Figure 132 High Density Drive, 20GB IDE


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Figure 133 PPC4/Analog Module Assembly

Figure 134 USB Keyboard


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Chapter 12 References These are Doble conference papers, arranged by year. 2006

Paper Title Author/Company Voltage Regulator Test Procedures and Test Data (A Progress Report)

Joe Brown, Bob Sarni, Doble Engineering Company

Field Experiences with SFRA

G. M. Kennedy ,C. Sweetser, T McGrail, Doble Engineering Company

2005

Paper Title Author/Company Advanced Diagnostics Support Critical Decision Making

Patrick M. McKenney, Entergy Vermont Yankee Nuclear Power

Field Experiences with SFRA

C. Sweetser, T McGrail, Doble

Report On Activities By Ieee Wg Pc57.149 And Cigre Wg A2.26 On Frequency Response Analysis Testing

Charles L. Sweetser, Doble Engineering Co., Watertown, MA USA Patrick Picher, Hydro-Québec, Varennes, Canada

2004

Paper Title Author/Company Measuring Frequency Responses of Transformer Windings - Powergrid Experience

A. Yadaw, S. Taneja , PowerGrid, India

Experimental and Numerical Investigation of Frequency Response Analysis Method for Diagnosing Transformer Winding Deformations

S. Jayasinghe, Z Wang, UMIST P. Jarman, NGT A. Darwin, Areva T&D

Investigation of Two 28 MVA Mobile Units Using Sweep Frequency Response Analysis

P. Prout, M. Lawrence, National Grid USA C. Sweetser, T McGrail, Doble

SFRA: An Efficient Tool for Decision Making Harry Fridman, Elco Industries Ltd., Israel Transformer Condition Assessment Greg Bennet, Excel Energy 2003

Paper Title Author/Company Transformer Diagnostics Using Frequency Response Analysis: Results for Fault Simulations

Simon A. Ryder, Alstom

A Comparison of the Swept Frequency and Simon A. Ryder, Stefan Tenbohlen, Alstom


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Impulse Response Methods for Making Frequency Response Analysis Measurements A Report on Activities by IEEE Standards Committee on Transformer FRA Testing

Dr. Ramsis Girgis, ABB Rowland James, Jr. Entergy Charles L. Sweetser, Doble

Experience with SFRA for Transformer Diagnostics

Dr. Tony McGrail, Doble

2002

Paper Title Author/Company The Need for and Use of Techniques to Assess the Mechanical Integrity of Transformer Windings

Alan Wilson, Doble Tony McGrail, National Grid

Experimental Investigations of the Repeatability of FRA Measurements: Experience with Sweep Frequency Response Analysis Measurements

Charles L. Sweetser, Doble

Transformer Fails Seven Years After Close Up Faults - FRA Diagnoses the Problem

John Lapworth, National Grid

2001

Paper Title Author/Company Testing Practices for Frequency Response Analysis

Charles L. Sweetser, Doble

Recent Developments Relating to the Detection of Winding Movement in Transformers by Frequency Response Analysis

John Lapworth, National Grid

ESBI Experiences with SFRA Tim Noonan, ESBI Frequency Response Analysis of the Leakage Impedance Used as a Power Transformer Diagnostic Tool

Librado Magallanes R., Ernesto López Azamar, Isaí Gallardo F., CFE

2000

Paper Title Author/Company Powergrid Experience with Frequency Response Analysis of Power Transformers

Ajay K. Kapur, Narendra S. Sodha, Barindra N. De Bhowmick, Alok Sharma Power Grid Corporation, India

Eurodoble Subcommittee Report on Frequency Response Analysis by the Swept-Frequency Method, and Development of a Test Guide

Timothy J. Noonan, ESB International Ireland


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1999

Paper Title Author/Company Transformer Winding Movement Detection by Frequency Response Analysis

John Lapworth, Tony J. McGrail, The National Grid

Case Study of Frequency Response Analysis Method

Alain Moissonnier, Electricite De France France

Frequency Response Analysis Using the Impulse Test Method as a Transformer Diagnostic Technique

A. John Vandermaar and May Wang, Powertech Labs Christopher P. Stefanski, ComEd, Barry H. Ward, EPRI

Experience in the Application Of Frequency Response Analysis

Sokom K. An, BPA, USA

1998

Paper Title Author/Company Belgian Experience with Frequency Response Analysis Measurements on 400/150/36 Kv, 150 Mva Shell Autotransformers

Paul Leemans, LABORELEC Belgium

1997

Paper Title Author/Company Experience with Failure Prevention in Power Transformers Using Frequency Response Analysis Technique

Ernesto Perez, Norcontrol, S.A. Spain

Power Transformer Condition Assessment and Renewal,Frequency Response Analysis Update

Timothy J. Noonan, ESB International

Life Assessment of 275 And 400 Kv Transmission Transformers

Paul N. Jarman, John A. Lapworth, Alan Wilson, The National Grid

1995

Paper Title Author/Company Mechanical Condition Assessment of Power Transformers Using Frequency Response Analysis

Timothy J. Noonan, ESBI, John A. Lapworth, National Grid


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Chapter 13 Miscellaneous The following two serial plates illustrate the voltage and current ratings of the M5200 and the M5300.


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Technical Specifications – M5200 & M5300

Physical: Instrument Weight—M5200 ......................................................................12 lbs./5.5.kg Instrument Weight—M5300 ......................................................................16 lbs./7.5.kg Dimensions—M5200 & M5300....................................... 10.0 H x 16.0 W x 15.5 D inch 25.4 H x 40.6 W x 39.4 D cm Transport Shock.............................................. High impact, molded, flame retardant, ABS designed to meet International Safe Transit Association Testing Procedure 1A for Resistance to Transport Shock and Vibration Electrical: Installation Classification .............................................................Overvoltage Class II AC Input Voltage ....................................................................................... 100-240 VAC AC Input Frequency ..................................................................................... 50 or 60 Hz AC Input Current—M5200.......................................................................................... 1A AC Input Current—M5300.......................................................................................... 1A AC Protection—M5200.............................................................................3A FAST BLO 3AG 250V FUSE AC Protection—M5200.........................................................................1.5 A FAST BLO 3AG 250V FUSE Environmental: Operating Ambient Temperature ....................................................................................................0 to 40° C (IEC-60068-2-1 and IEC-60068-2-2) Operating Relative Humidity...........................................................................10% to 90% non-condensing (IEC-60068-2-56) Storage Ambient Temperature ............................................................................................... -20° to 70° C (IEC-60068-2-1 and IEC-60068-2-2) Storage Relative Humidity.............................................................................5% to 90% non-condensing (IEC-60068-2-56) Pollution Degree............................................................................................................ II Operating Altitude......................................................................................2000M (Max)


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A Analysis 13, 32, 39, 97, 98, 99, 100, 101, 121 Apparatus Details 46 AutoTransformers 109

B BNC 27

C Clear Traces 96 coaxial 17 conference papers 135 correlation 39, 98, 101 cursor 90, 91, 94, 101

D Data Manager 32, 41, 42, 67, 69, 86 Data Source 66, 67, 68, 69,74, 86, 87, 90 Data Tree 68

E Edit Apparatus 33, 46 editors 47, 48 Exporting 51, 52, 71

F Firewall 29 folder 66, 68, 69, 71, 72

G Ground Continuity 81

H Hardware 15, 16

I Importing 51, 52, 65, 72, 74

L lead

black 63, 108 red 63, 108

Linear 95, 96 location18, 29, 33, 46, 48, 50, 51, 53, 66, 69, 74, 78, 86, 90, 126, 128 Location33, 41, 47, 48, 50, 51, 52, 53 67, 72, 73, 74, 75, 76, 78, 79, 86, 87

Log 95

M Magnitude ix, 32, 36, 37, 40, 41, 118 Manufacturer 86

N New Range 94

P Parts List 15, 129 Phase 32, 36, 37, 40, 60, 111, 115, 118, 119 Plot Property 45 power switch 26, 28 Print 33, 102, 103, 104 Print Preview 33, 102, 103

R Running a Test 75

S Safety 19, 23, 24 Self Test 81, 82 Software 15, 19, 29, 30, 32, 65, 104, 128, 129 software version 35

T Tabulation 32, 40 tap position 29, 107, 108, 121 Template 53, 56, 57, 62, 63, 64, 65, 77, 78 Test Cables 17 Test Equipment 46, 47, 48, 50, 51, 53, 60, 75, 76, 87 Test set 46 Testing organization 29, 46 Three Winding Transformers 110 trace name 45, 78 transfer function 13, 21, 22, 117, 118, 119 Transformer24, 25, 29, 41, 46, 53, 54, 58, 59, 65, 72, 74, 75, 87, 89, 90, 111, 11Trouble Shooting 82 Two Winding Transformers 109 two-port network 21

W Waveform 32, 38, 83

Z zoom 94, 114


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maximum effective frequency

doble engineering company

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