ama00e tp001 ra site commissioning procedure for electrical systems

8/11/2019 AMA00E TP001 RA Site Commissioning Procedure for Electrical Systems

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Replaces Customer Code ALSTOM Document Code

AMA/00/E/----------/TP/001Responsible dept.

TYCC-INCreated by

Samy A-L.Checked by

Gupta S. Approved by

Varshney S.Format

A4Originator

POW R

GAS BUSINESS

Document Type

Test ProcedureDocument Status

Electronically releasedTitle, Subtitle

Site Commissioning Proceduresfor Electrical Systems

Identification number

1AHA609989Rev.

ADate

10.12.2012Lang.

enSheet

1/3

Template No.: Att.1 to >XYZ/00/-/01-----001/PPI/001 A< (released with corresponding Project Procedure >XYZ/00/-/01-----001PPI/001<)

© ALSTOM 2012. All rights reserved. Please consider the environment before printing this document.

Site Commissioning Procedures for ElectricalSystems

Owner

Project

AL–MANSURYA GAS TURBINE POWER PLANT (PHASE I)

Space for Stamping (Review and Validation status)

Cross checked

Department Name Date Signature

Revision History

Rev. Revision Date Created by Checked by Approved by Brief Description

Description Current Revision



Electronically released

Originator

LSTOM

POW R


1AHA609989Rev.

ADate

10.12.2012Lang.

enSheet

2/3

© ALSTOM 2012. All rights reserved.

Table of Contents:

1 OBJECTIVE .......................................................................................................................... 3

2 LIST OF SITE COMMISSIONING PROCEDURES .............................................................. 3




Originator

LSTOM

POW R


1AHA609989Rev.

ADate

10.12.2012Lang.

enSheet

3/3

© ALSTOM 2012. All rights reserved.

1. OBJECTIVE

The purpose of this document is to list all the site commissioning procedures used forelectrical systems at Al-Mansurya Site.

2. LIST OF SITE COMMISSIONING PROCEDURES

Document Number ID Number DESIGNATION

GAS/00/E/153B---002/TP/101 1AHA608688Site Commissioning Procedure For PowerTransformer Field Testing

GAS/00/E/153B---002/TP/102 1AHA608717Site Commissioning Procedure For CT & PT FieldTesting

GGG/00/E/TEC-------/TP/404 PSP29 A43047 Neutral Earthing Resistor Field Testing

GGG/00/E/TEC-------/TP/405 PSP29 A43042 HV Surge Arrester Field Testing



Main Contractor

Alstom Switzerland) Ltd. , Brown Boveri Strasse 7, CH 5401-Baden Replaces Customer Code ALSTOM Document Code

GAS/00/E/153B---002/TP/101Responsible dept.

GSEEECreated by

Schuele N.Checked by

Hug R. Approved by

Huser J.Format

A4Originator Document Type



Title, Subtitle

Site Commissioning Procedure

Identification number1AHA608688

Rev. Date Lang. Sheet

SITE COMMISSIONING PROCEDURE

FOR POWER TRANSFORMER FIELD TESTING

Projects and Customer’s Information:

Plant Name, Project:

Customer:

Acceptance Authority:

Customer Order No.: ALSTOM Order No.:

Notification Periods: Measuring System:

QA coordination:


Cross checked


Revision History


ADescription current Revision:

First Issue




For Power Transformer Field Testing


1AHA608688

DRAFT

TABLE OF CONTENT

1 INTRODUCTION 3

1.1 PURPOSE 3

1.2 AREA OF APPLICATION 3

1.3 REFERENCE DOCUMENTS 3

1.4 ABBREVIATIONS 3

2 SAFETY SYMBOLS 4

3 List of commissioning TOOLS 5

4 HEALTH AND SAFETY 5

4.1

SPECIAL SAFETY PRECAUTION 5

5 POST-INSTALLATION CHECKS 6

5.1 DATA RECORDING 6

5.2 VISUAL INSPECTION 6

6 PRE-commissioning 7

6.1 EARTH RESISTANCE CHECKS 7

6.2 TRANSFORMER ACTIVE PART CHECKS 7

6.3 AUXILIARY CIRCUIT CHECKS 10

6.4 CURRENT TRANSFORMERS 12

6.5

TAP-CHANGERS 12

6.6 POWER CABLES AND CONNECTIONS 13

7 COMMISSIONING 13

7.1 BEFORE THE ENERGISATION 13

7.2 FIRST ENERGISATION – NO LOAD CHECKS 14

7.3 HOT COMMISSIONING (ON LOAD CHECKS) 14

7.4 RECORDS 14

8 ANNEX 15

8.1 TRANSFORMER CONNECTIONS 15

LIST OF FIGURES

FIGURE 1: TRANSFORMER VECTOR GROUP DETERMINATION TEST RESULT PLOT. 9

FIGURE 2: SIMPLIFIED BUCHHOLZ RELAY ON TRANSFORMER. 10

FIGURE 3: SIMPLIFIED PRESSURE RELIEFE VALVE. 11

FIGURE 4: OFF CIRCUIT TAP-CHANGER (OCTC) SAFETY PADLOCK. 12

FIGURE 5: THREE-PHASE TRANSFORMER CONNECTIONS 15






1AHA608688

DRAFT

3 LIST OF COMMISSIONING TOOLS

The following is a list of the main test equipment necessary in order to carry out all the testing of the

equipment covered by this procedure:

Warning / Caution Notices

Anti-personal barriers

Thermometer

Hygrometer

Insulation Resistance Tester (Megger) up to 5 kV

Digital Multimeter

400 VAC three-Phase Supply with MCB

Phase Rotation Tester

Chronometer

Test leads

CT tester (optional / if available)

Note: Tools, which need to be calibrated, must have a valid calibration certificate traceable to

internationally accepted standards.

4 HEALTH AND SAFETY

The work outlined in this procedure must only be carried out by persons who are competent and

appropriately qualified engineers in the appropriate disciplines. These persons shall:

Be aware of all Site Safety Procedures & Statutory Regulations and fully comply with them.

Recognize the hazards, which can arise when working on energized apparatus and take all

necessary precautions.

Recognize the hazards of induced current and take all necessary precautions.

Ensure that two people are always present when working with live equipment.

Use approved tools and equipment.

Wear always your personal protective equipment. Read the manufacturer's O & M manuals and get familiar with the safety regulations.

4.1 SPECIAL SAFETY PRECAUTION

When work is performed on a transformer connected to the system, proper earthing tools must be

installed on HV & LV sides.

Before any voltage or current injection, check that all Current Transformer secondary circuits are

closed.






1AHA608688

DRAFT

5 POST-INSTALLATION CHECKS

The following section describes all activities and tests to be carried out on transformers prior to start

any pre-commissioning activities.

5.1 DATA RECORDING

Test sequence:

The data of the transformers shall be taken directly from its nameplate (if applicable) and check against

the technical specifications.

5.2 VISUAL INSPECTION

The transformer shall be first inspected visually. Special attention shall be paid to any damage that

could have occurred during transport or installation. Check that the transformer, the control cabinet and

all accessories are cleaned and touch up painted if needed.

5.2.1 Valves positions

Test sequence:

Check that all valves are in the position indicated either at the general arrangement plan or at the

indicator panel meant for them.

5.2.2 Expansion tank

Test sequence:

Check the oil level of the compartment(s).

Check the priming of the non-return valve.

5.2.3 Drains

Test sequence:

Check the drains of the upper points.

5.2.4 Air dryer

Test sequence:

Check proper colour of the desiccant, presence of proper oil level in the dehydrating (desiccant)

breather.

5.2.5 Oil Leaks

Test sequence:

Check the entire transformer for oil leaks.

5.2.6 General

Test sequence:

More generally, carry out all other checks listed on test certificates.






1AHA608688

DRAFT

6 PRE-COMMISSIONING

The following section describes all tests to be carried out on transformers prior to start any live

integrated commissioning activities.

6.1 EARTH RESISTANCE CHECKS

Test sequence:

Check that connections to earth are properly made.

Measure the resistance between tank and ground connection and tank and bushing flange with a

battery-driven ohmmeter on at least 4 different locations.

Record results on test certificates.

6.2 TRANSFORMER ACTIVE PART CHECKS

6.2.1 Insulation Measurement Tests

6.2.1.1 Core / Tank (if test link is provided)

The purpose of this test is to ensure that the core to tank insulation has not sustained any damage

whilst in transit and installation.

Test sequence:

Disconnect the earth links from the core and tank earthing terminalsMegger with appropriate voltage (500V to 1kV) for one minute between the following terminals:

∙ Core to Earth

∙ Core to Tank

∙ Tank to Earth

Record results on test certificate (minimum acceptable value is > 1k/V).

Reconnect the earth links to the core and frame terminals.






1AHA608688

DRAFT

6.2.1.2 Windings

Before starting the test, disconnect Neutral Star Point Earth connections and any measurement

devices such as PT's (where applicable).

Test sequence:

Megger with appropriate voltage (500V to 2.5 kV) for one minute between the following terminals:

For two-winding transformer

∙ HV and LV

∙ HV and earth

∙ LV and earth

For three-winding transformers

∙ HV and LV1

∙ HV and LV2

∙ LV1 and LV2

∙ HV and earth

∙ LV1 and earth

∙ LV2 and earth


6.2.2 Voltage Ratio Measurement

Test sequence:

Ensure that HV and LV connections are disconnected (or isolated).

Connect a 3-phase 400 VAC source on the HV terminals.

Measure and record simultaneously voltages on the HV and LV terminals.

Calculate HV / LV ratios.


Notes:

As per contract requirement, this test may be required for different transformer tap positions (see the

relevant Transformer Inspection and Test Plan for details).

If Automated Transformer Analyser equipment (i.e. Doble) is available on site, the use of it will be a

valuable alternative method to carry out the tests mentioned above.

6.2.3 Three-Phase No-Load Current with Low Voltage Supply

Test sequence:

Supply the HV or LV windings with three-phase 230 or 400 V AC.

Measure the current with 3 digital millimetres, for at least three positions.

Record results on the test certificates.






1AHA608688

DRAFT

6.3 AUXILIARY CIRCUIT CHECKS

6.3.1 Auxiliary Circuit Insulation Test

Test sequence:

Apply for one minute a test voltage of 500 VDC (max.) to:

Wiring to earth.

Pump motors to earth.

Fan motors to earth.


6.3.2 Auxiliary Operation Test

Test sequence:

Supply the power and control circuits with the nominal voltage and check:

The phase sequence with phase sequence tester.

The settings for over- and under voltage supervision (if applicable).

The correct rotation of fans and / or pumps visually.

The current of fans and pumps.

The starting sequences (with chronometer).

The proper operations of the oil flow indicator (if applicable).

The local control cabinet hater is connected and in operation.

The thermal overcurrent protection relays of the motors are set according to the rated -current

that is stamped on the rating plate.

Record results on test certificate.

6.3.3 Protective relay (Buchholz)

Test sequence:

Check at the terminals of the cabinet that the Buchholz

manually activated (e.g. with test push-button) with the device

intended for this purpose, transmits electrically the indicating of

its operation according to the electrical diagram (alarm and

tripping).


Figure 2: Simplified Buchholz relay on transformer.






1AHA608688

DRAFT

6.3.4 Tap-changer protective relay

Test sequence:

Check at the terminals of the cabinet that the protective relay manually activated (e.g. with test push-

button) with the device intended for this purpose, transmits electrically the indicating of its operation

according to the electrical diagram (alarm and tripping).


6.3.5 Pressure relief valve

Test sequence:

Check the values indicated to the cover.

Check the position indicator.

Test the contact (if there is one).


Figure 3: Simplified pressure reliefe valve.

6.3.6 Oil level indicator

Test sequence:

Check at the terminals of the cabinet the signals for low and high level of the transformer and tap-

changer compartment.


6.3.7 Oil thermometer indicator

Test sequence:

Check the device according to the manufacturer’s service manual.

Check oil temperature readings against winding temperature. It should be the same.


6.3.8 Winding thermometer indicator

Test sequence:

Standardizat ion and ver i f ication o f prop er operat ion are checked at the factory.

Check manually, with the mechanical test device integrated to the apparatus, the closing of the

different circuits, and the proper electrical transmission of commands according to the electrical

diagram.

The modif icat ion o f the ini t ial sett ing of the heating circui t , ei ther at the transformer for th e adjustment

current or at the adjustm ent resistance, can only be carr ied out with the agreement of the factory.

Check winding temperature readings against oil temperature. It should be the same.

If presence of transducer, check that the output mA is showing the correct value.







1AHA608688

DRAFT

6.3.9 Fire detectors

Test sequence:

Check that the fire fighting system is completed and tested.

Check that the distance between the HV bushings and fire fighting system are sufficient.

6.4 CURRENT TRANSFORMERS

Perform the testing according to the “site commissioning procedure for CT and VT field testing”.

GAS/00/E/153B---002/TP/102

Note:

Take care for voltage induced to the other windings during this checks.

6.5 TAP-CHANGERS

6.5.1 Off circuit tap-changer (OCTC)

Test sequence:

Check the locking in each position.

Check the electrical position indicator of each position.


WARNING

The OCTC shall be operated ONLY when the transformer is Off-Circuit, i.e., totally isolated

from the power supply, otherwise there can be heavy arcing at tap connections which canresult in a fire / explosion hazard.

Remark:

Means of protecting the OCTC’s from unauthorised operation is provided by using

pad-locking arrangement at designated tap position.

Figure 4:Off Circuit Tap-Changer (OCTC) safety padlock.

6.5.1.1 Pre-operational checks

Test sequence:

Using the emergency crank, bring the motor drive unit to a position distant from the extreme positions

(middle position).

Check the similarity of the displayed switches and make sure that the tap-changer head and the

selector switch rotate before the motor drive unit does.

Check that the motor drive unit and the tap-changer turn in the same direction.






1AHA608688

DRAFT

6.6 POWER CABLES AND CONNECTIONS

6.6.1 HV / MV cables and bus bar links

Test sequence:

Ensure that connections to lines, bus bars are properly made and tightened by erection.

Check that shield grounding of the cables is in accordance with the grounding concept.

Check that all cables connected to bushings are properly supported.

7 COMMISSIONING

The following section describes all steps to be followed in order to commission in proper and

methodical manner the power transformer.

7.1 BEFORE THE ENERGISATION

Before energizing the transformer, it should be visually inspected and the following items checked:

The oil level in the oil filled compartments.

The drying agent and the oil level in the dehydrating breather.

Check that all valves are set at the right position and locked, where applicable.

Check that the gas-operated relay is purged of air.

Check for possible leakage.

Check that all temporary grounds have been removed from conductors.

All protective, alarm and monitoring circuits are operational and in service. Check that all CT secondary circuits are closed.

The automatic cooling control of the transformer is in operation.

The on-load tap changer control is selected to REMOTE operation.

Record ambient conditions, oil and winding temperatures.

Ensure that oil samples are correctly taken and the result is accepted.

Ensure that the area is made secure and suitable warning notices are in place.

Ensure that fire fighting / deluge system is available and operational.

Ensure that all equipment have been restored to suitable state and ensure that the

documentation due for permanent energization of transformers, as per site management rules,

is available and signed by all relevant parties.







1AHA608688

DRAFT

7.2 FIRST ENERGISATION – NO LOAD CHECKS

WARNING

When the place is secure, proceed with transformer energization by closing remotely (no exception

allowed) the corresponding circuit breaker.

DANGER

Never climb up on a transformer, while it is energized!

After energizing, the transformer has to be kept under careful observation:

Observe and record oil, winding and ambient temperature for the first 24 hours.

Observe current, load (MW / MVAr) and voltage.

Watch for unusual noise.

Watch particularly for any sudden changes.

Reset maximum indicating pointer of temperature Indicators (if applicable).

Take oil samples for Gas-In-Oil Analysis according to ITPL.

Record results on the test certificates / add the DCS 24h trend.

7.3 HOT COMMISSIONING (ON LOAD CHECKS)

After reaching nominal load for at least 8 hours:

Observe and record oil, winding and ambient temperature.

Watch for unusual noise.

Watch particularly for any sudden changes.

Reset maximum indicating pointer of temperature Indicators (if applicable).

Take oil samples for Gas-In-Oil Analysis according to ITPL.

Record results on the test certificates / add the DCS 8h trend.

7.4 RECORDS

All test records shall be filed in accordance with the Site Quality Plan.






1AHA608688

DRAFT

8 ANNEX

8.1 TRANSFORMER CONNECTIONS

Extract from IEC 60076-1: Power Transformers – Part 1 – General, Annex D

Figure 5: Three-phase transformer connections



Main Contractor

Alstom Switzerland) Ltd. , Brown Boveri Strasse 7, CH 5401-Baden Replaces Customer Code ALSTOM Document Code

GAS/00/E/153B---002/TP/102Responsible dept.

GSEEECreated by

Schuele N.Checked by

Hug R. Approved by

Huser J.Format

A4Originator Document Type


Electronically releasedTitle, Subtitle


For CT and VT Field Testing


1AHA608717Rev.

ADate

23 08 2012Lang.

enSheet

1/18

SITE COMMISSIONING PROCEDURE

FOR CT AND VT FIELD TESTING

Projects and Customer’s Information:

Plant Name, Project:

Customer:

Acceptance Authority:

Customer Order No.: ALSTOM Order No.:

Notification Periods: Measuring System:

QA coordination:


Cross checked


Revision History


ADescription current Revision:

First Issue






1AHA608717

The inspection and test plan does not release the subcontractor / manufacturer from his obligation to take all steps necessary to

Table of Content

1. INTRODUCTION 3

1.1 PURPOSE 3

1.2 AREA OF APPLICATION 3

1.3 REFERENCE DOCUMENTS 3

1.4 ABBREVIATIONS 3

2. SAFETY SYMBOLS 4

3. LIST OF COMMISSIONING TOOLS 5

4. HEALTH AND SAFETY 5

4.1 SPECIAL SAFETY PRECAUTION 5

5. COMMISSIONING 6

5.1 DATA RECORDING AND VISUAL INSPECTION 6

5.2 INSULATION MEASUREMENTS 6

5.3 RATIO CHECK 7

5.4 POLARITY CHECK 10

5.5 CT MAGNETIZING CHARACTERISTIC 14

5.6 BURDEN AND OHMIC CT-WINDING RESISTANCE MEASUREMENT 16

6. LITERATURE 17

7. ANNEX 18

7.1 TRANSFORMER RESTRICTED E/F (REF) PROT. 87NT, HIGH IMPEDANCE 18

List of Figures

Figure 1: CT ratio check with primary current injection 7

Figure 2: Multiplying the primary current by looping the test leads several times 7

Figure 3: CT ratio check on a multi-core CT 8

Figure 4: CT ratio check with secondary voltage injection 8

Figure 5: Ratio check with secondary voltage injection on a built in transformer CT 9

Figure 6: VT ratio check with primary voltage injection 9

Figure 7: CT polarity check with DC current source 10

Figure 8: CT polarity check with secondary voltage injection on a transformer bushing CT 11

Figure 9: VT polarity check with DC current source 12

Figure 10: VT polarity check with primary voltage injection 13

Figure 11: CT magnetizing characteristic measurement with secondary voltage injection 14

Figure 12: CT magnetizing characteristic 15

Figure 13: CT/VT burden measurement with secondary voltage injection 16

Figure 14: Ohmic winding resistance measurement of CT 17

Figure 15: Example to test 87NT with high impedance measuring principle and relay O/C function. 18






1AHA608717


1. INTRODUCTION

1.1 PURPOSE

The intention of this procedure is to make an efficient and safe testing of CT’s and VT’s.

This Document contains detailed information and instructions about the testing of current and

voltage transformers and the user has to read it carefully and thoroughly before starting the test.

By the end of this procedure the following goals will have been met:

All CT’s tested

All VT’s tested

1.2 AREA OF APPLICATION

The procedure is applicable to current and voltage transformers.

1.3 REFERENCE DOCUMENTS

System commissioning ITPL, including test certificates.

Equipment schematic diagrams.

Plant specific single line / protection single line diagram.

Test certificates for CT and VT

Factory test certificates

1.4 ABBREVIATIONS

Abbrev. Meaning

AC Alternating Current

DC Direct Current

CT Current Transformer

VT Voltage Transformer

Un Nominal Voltage

In Nominal CurrentH&S Health and Safety

ITPL Inspection and Test Plan

P&ID Process and Instrumentation Diagram

Q&A Questions and Answers

QA Quality Assurance

TOP Turn Over Packages






1AHA608717


2. SAFETY SYMBOLS

The user has to consider the following symbols used within this document:

DANGER

Danger indicates an imminently hazardous situation that if not avoided, will result in deathor serious injury. This signal word is to be limited to the mostextreme situations.

WARNING

Warning indicates a potentially hazardous situation that if not avoided, could result indeath or serious injury.

CAUTION

Caution indicates a potentially hazardous situation that if not avoided, may result in minoror moderate injury.It may also be used to alert against unsafe practices.

Note

Note indicates an important instruction or the best practices. It may also be used to alertagainst mechanical damage to the equipment.

DANGER

High voltage / Electrical shockHazard of electrical shock if carry out work on life electrical systems will causedeath or major injury.

Apply the 5 safety rules when working at any electrical equipment:

- Isolate

- Lock out / Tag out

- Check voltage free state

- Apply earth and short-circuit

- Cover or block neighboring energized equipment and areas

Avoid wet surfaces!






1AHA608717


3. LIST OF COMMISSIONING TOOLS

The following is a list of the main test equipment necessary in order to carry out all the testing of the

equipment covered by this procedure:

Insulation resistance tester (Megger) 500VDC

Variable current- / voltage source

(Capacity according nameplate of CT / VT, current source: 0-100A, voltage source: 0-300V)

Voltage transformer to increase the range of the voltage source if necessary. E.g. 0.1 / 3kV.

Current clamp

Digital Multimeter

Analogue volt- / ammeter (with center zero position)

Battery (e.g. 6V from commissioning tools)

Test leads CT-Tester (optional / if available)

Note: Tools, which need to be calibrated, must have a valid calibration certificate traceable to

internationally accepted standards.

4. HEALTH AND SAFETY

The work outlined in this procedure must only be carried out by persons who are competent and

appropriately qualified engineers in the appropriate disciplines. These persons shall:

Be aware of all Site Safety Procedures & Statutory Regulations and fully comply with them. Recognize the hazards, which can arise when working on energized apparatus and take all

necessary precautions.

Recognize the hazards of induced current and take all necessary precautions.

Ensure that two people are always present when working with live equipment.

Use approved tools and equipment.

Wear always your personal protective equipment.

4.1 SPECIAL SAFETY PRECAUTION

When work is performed on equipment connected to the system, proper earthing tools must be

installed on HV & LV sides and the isolation boundaries of the test area must be clearly defined.

Before any voltage or current injection, check that all Current Transformer sec. circuits are closed.

Special attention shall be paid to:

That no part is accidentally energized by VT primary injection and during megger-testing.

That no current is injected in any circuits accidentally (danger of equipment damage or faulty

trips).






1AHA608717


5. COMMISSIONING

5.1 DATA RECORDING AND VISUAL INSPECTION

The CT’s /VT’s shall be first inspected visually. Special attention shall be paid to any damage that

could have occurred during transport or installation.

Check also (as applicable)

the support structures,

the tightness of the transformers and

the electrical connections.

The data of the transformers shall be taken directly from its nameplate (if applicable) then compared

with the requirements and recorded on the test certificate.

5.2 INSULATION MEASUREMENTS

Test the secondary windings of the transformers with a Megger (500VDC). Ground connections inthe primary or secondary loop shall be disconnected first.

CT: secondary winding ground (+ primary winding)

VT: secondary winding ground + primary winding

The readings should not be below 1 MOhm, if not indicated by manufacturer.

Where reasonable, also the primary winding of a VT should be “meggered” (in many cases, the

grounding cannot be removed and thus an insulation test is not possible). The primary winding must

be “meggered” in every case where a damage is suspected.

VT: primary winding ground + secondary winding






1AHA608717


5.3 RATIO CHECK

5.3.1 CT RATIO CHECK

Injection of a primary current and simultaneous measuring of the secondary current.

Test sequence:

Set up the test / measuring equipment according to figure1.

Check if secondary CT circuit is closed! Check also the fuse of Ammeter.

Adjust current-source to minimum and switch it on.

Increase the primary current slowly by watching the secondary current indication. If no

secondary current or a current other than the expected one is showing switch off the current

source and recheck the set up.

Increase the primary current to a stable value and take the reading.

Figure 1: CT ratio check with primary current injection

Due to the capacity of the test equipment, normally only a current far below the CT nominal current

can be injected. In case of a doughnut - CT, the primary current can be multiplied by looping the test

leads several times through the CT (see figure 2).

Figure 2: Multiplying the primary current by looping the test leads several times

Variablecurrent

source

A

Variablecurrentsource

A A






1AHA608717


For CT’s with more than one core, the remaining circuits must be shortened (never operate a CT

with an open secondary circuit!)

When more than one core exists, all cores can be

tested simultaneously, see figure 3

Figure 3: CT ratio check on a multi-core CT

5.3.2 ALTERNATIVE CT RATIO CHECK OR VOLTAGE METHODIn some situations it might be difficult injecting a primary current to check the CT ratio (e.g. bushing

CTs). In this case it is possible to inject a voltage on the CT secondary side and measure the

voltage on the primary side. The voltage ratio is the inverse of the current ratio.

ondary

primary

primary

ondary

I

I

U

U

sec

sec = CT-turns ratio

A relatively low voltage (e.g. 50 -100 V AC) is sufficient. Take care that the saturation voltage must

not be reached in any case!

Test sequence:

Set up the test / measuring equipment according to figure 4.

Increase the secondary voltage slowly to the desired value.

Read and record the primary voltage

Figure 4: CT ratio check with secondary voltage injection

Variable

current

source

A

A A A

Variable

voltage

source

V

V






1AHA608717


The figure below shows the testing configuration as an example on a built in transformer CT.

Figure 5: Ratio check with secondary voltage injection on a built in transformer CT

5.3.3 VT RATIO CHECK

To check the VT ratio, a voltage on primary side shall be injected and the voltage at secondary side

must be measured simultaneously.

To avoid accidentally energizing of any parts, the VT must be disconnected from the busbar (or the

part of the busbar must be insulated from neighbouring equipment.

Test sequence:


Raise the primary voltage slowly to the desired value.

Read and record the secondary voltage.

Figure 6: VT ratio check with primary voltage injection

Variable

voltage

source V

V

PowerTransformer

Windings

Busbar

Disconnected!

Variable voltage sourc

V V






1AHA608717


5.4 POLARITY CHECK

5.4.1 CT POLARITY CHECK WITH A DC SOURCE

In many applications, the right polarity is essential for their correct functioning (power measurement,

differential protection, etc.).

Before starting with the test, the designations and locations for P1, P2 and S1, S2 must be

compared between the diagram and the field.

The test has the purpose to verify the corresponding polarity like they are supposed to be according

the diagram.

Verifying this, it is not essential in which energy flow direction the designations for P1 and P2 are

located. Important is that the primary designation P1 corresponds with the secondary designation

S1 (and P2 with S2)!

To check the polarity, a DC-source is switched on and off to the primary side of the CT. As thismeans practically a short circuit for the current source, it must be short circuit proven. A suitable

source can be a battery (e.g. 6 or 9V) with low capacity that is connected over a push button to the

CT (Instead of a push button, the contact can be achieved by plugging in and out a prepared cable).

To limit the current, it might be necessary to connect a resistor in series.

When closing the circuit, the meter on the CT secondary side shows a positive current peak, when

opening the circuit, the meter on the secondary side shows a negative current peak. To measure

this, an analogue meter with centre zero position suits best.

(Variation: Instead of current, the voltage can be measured on the CT secondary side with the same

result).

Test sequence:

Set up the test / measuring

equipment according to figure 7.

Close the primary circuit with the

push button positive peak on

secondary side.

Open the primary circuit

negative peak on secondary side.

Record the results and verify with

the diagram.

Figure 7: CT polarity check with DC current source

For valid results, the correct polarity of the test connections is essential!

R (option)

_ + DC current

source

P1

P2 S2

S1

V

+ A

Push-

button

Analogue

meter

_






1AHA608717


5.4.2 CT POLARITY CHECK WITH SECONDARY VOLTAGE INJECTION

As an alternative, the polarity can also be verified with the voltage method. It is a faster way, when

the ratio was checked with the voltage method beforehand.

The principle is based on the addition of the voltages. When the polarity is correct, i.e. according our

expectations, the measuring voltage Um is the sum of the CT secondary voltage U1 and the CT

primary voltage U2. If the polarity were wrong, the measuring voltage Um would be the difference

between U1 and U2.

k

U U

12 k= CT - turns ratio

Figure 8: CT polarity check with secondary voltage injection on a transformer bushing CT

Test sequence:


Increase the secondary voltage U1 slowly to the desired value.

Record the voltages U1, U2 and Um correct polarity if Um = U1 + U2.

Switch off the voltage source

Remark:

Double-check the result: swapping the cables “a” and “b” between L1 and L2 can change the

direction of U2. This "wrong polarity" results then in Um = U1 - U2.

A valid measuring result can only be achieved if the set up is done carefully, with correctpolarities of all connections!

ba

U1

Um

U2

L3L2L1

P1

P2

Um

Um

U2

U1

U2U1

Variable

voltagesource, AC

V

V Um = U1 + U2 (correct polarity)

V

Um = U1 – U2

( wrong polarity

PowerTransformer

Windings

S2 S1






1AHA608717


5.4.3 VT POLARITY CHECK WITH A DC SOURCE

This test is similar to the CT polarity check.

Test sequence:


Close the primary circuit with the push button positive peak on secondary side.

Open the primary circuit negative peak on secondary side.

Record the results and verify with the diagram.

For valid results, the correct polarity of the test connections is essential!

Figure 9: VT polarity check with DC current source

R (option)

_

+

Busbar

_ +

DC currentsource

P1

P2 S2 V

Pushbutton

Analogue

meter

Disconnected!

V

S1






1AHA608717


5.5 CT MAGNETIZING CHARACTERISTIC

To verify the CT-type, i.e. metering or relaying (for protection), the magnetizing characteristic

(excitation characteristic) shall be measured. The purpose of this test is to decide if the correct CT-

type is installed.

On the secondary side of the CT, a voltage source must be connected. According to the CT

characteristic, the necessary voltage can vary from 200 Vac up to 800Vac.

To reach this level, the different sources on the test device must be connected in series (e.g. on the

Sverker). If this is not enough, it might be necessary to connect an additional transformer in series

to the variable voltage source.

It has to be ensured that the primary circuit of the CT is open (e.g. no closed loop over generator

windings).

The characteristic of the CT, respectively its saturation voltage must be known beforehand (factory

test sheet).

Test sequence:


Make sure, the CT primary circuit is not shorted.

Increase the voltage slowly close to the saturation value.

CAUTION

Close to the saturation voltage, the current will increase nonlinear and rapidly!

At this point the voltage must not be increased further! Absolute maximum is IN of CT.

Record the values for voltage and current

Decrease the voltage stepwise down to zero and record the values for voltage and current.

Compare the measurement results with the factory data.

Figure 11: CT magnetizing characteristic measurement with secondary voltage injection

Variable

voltage

source

V

A

Transformer

100/3000V

(optional)






1AHA608717


The figure below shows a CT magnetizing characteristic as an example.

The voltage and current values are for illustration only and do not give any fixed limitations. This

depends on the CT-type.

Figure 12: CT magnetizing characteristic

Note:

Field-testing cannot be that accurate. Therefore the measured values for current can deviate

considerably from the curve obtained at the factory.

Important is the verification of the saturation voltage. With this result, the significant difference

between metering- and protection CT’s can be noticed.

CT secondary excitation characteristic

1

10

100

1000

V o l t s

AmperesRestricted range for test Measuring range

0.001 0.01 0.02 0.03 0.05 0.07 0.1 0.5 10 100






1AHA608717


5.6 BURDEN AND OHMIC CT-WINDING RESISTANCE MEASUREMENT

5.6.1 BURDEN MEASUREMENT

This measurement serves to verify the external burden, connected to the CT and VT in normal

operation. Before injection, a target / loop check of the cables must be done.

The injection shall be done with nominal values.

E.g. CT-ratio 12000/5A injection 5A and VT-ratio 21000/120V injection 120V

The injection has to be done close to the CT / VT in order to measure the whole secondary circuitburden. With the measured values for voltage and current, this burden, in VA, must be calculated.This amount of the external burden shall not exceed the value given on the nameplate. (In contraryor when doubts remain, the engineering department shall be informed.)

Test sequence:


Increase the voltage / current slowly to the nominal value.

Record the values for voltage and current.

CAUTION

When doing burden measurements, the effect of the injection has to be thought beforehand.

E.g. generator protection functions could be activated!

Figure 13: CT/VT burden measurement with secondary voltage injection

CT or

VT

Variable

source

V

Load

e.g. Gen. prot.

Metering,..

A






1AHA608717


5.6.2 OHMIC CT- WINDING RESISTANCE MEASUREMENT

At this stage, also the ohmic winding resistance (secondary) of the CT shall be measured andrecorded.

Measure the CT-secondary value with an ohmmeter.

Record the values and compare them with the factory test results.

Figure 14: Ohmic winding resistance measurement of CT

6. LITERATURE

ANSI/IEEE Standard C57.13.1-1981: IEEE Guide for field testing of relaying current transformers.






1AHA608717


7. ANNEX

7.1 TRANSFORMER RESTRICTED E/F (REF) PROT. 87NT, HIGH IMPEDANCE

This measurement serves to verify the wiring of the built-in CT’s for the protection function 87NT.

With this arrangement the test voltage can only be connected outside the protected zone.

Figure 15: Example to test 87NT with high impedance measuring principle and relay O/C function.

Test sequence:

Set up the test / measuring equipment according to Figure 15 .

Turn on the power supply and measure the current in each CT and to the relay.

With a correct wiring and CT polarity the summation current to the relay is theoretically zero mA.

But in practice there will be a small difference because of production differences of the different CT’s.

Description I primary L1 sec. L2 sec. L3 sec. N sec. Relay

Power supply on L1 … A … mA 0 mA 0 mA … mA ≈ 0 mA

Power supply on L2 … A 0 mA … mA 0 mA … mA ≈ 0 mA

Power supply on L3 … A 0 mA 0 mA … mA … mA ≈ 0 mA



Cross checkedDepartment Name Date Signature

Replaces Derived from ALSTOM Document Code

GGG/00/E/TEC-------/TP/404Responsible dept.

PEI FRCreated by

S. BaderChecked by

M. André Approved by

H. DoulatFormat

A4Legal Owner

abcdPT-PEPlant Business

Document Type


ApprovedTitle, Subtitle

Commissioning ProcedureFor Neutral Earthing Resistor

Field Testing


PSP29A43047Rev.

ADate

15.01.2007Lang.

enSheet

1/7

Template No.: GGG/00/-/EQA---/FT/303D (released with Work Instruction GGG/00/-/EQA---/WI/306)© ALSTOM 2012. All rights reserved.

Electrical Commissioning Engineering Manual

Site Commissioning ProcedureFor Neutral Earthing Resistor Field Testing

Table of Contents:

1

PURPOSE ................................................................................................................ 2

2 AREA OF APPLICATION .......................................................................................... 2

3 REFERENCE DOCUMENTS........................................................................................ 2

4

TERMINOLOGY – DEFINITION – ABBREVIATIONS .................................................. 2

5 LIST OF COMMISSIONING EQUIPMENTS ............................................................... 3

6

HEALTH AND SAFETY .............................................................................................. 4

7

SPECIAL SAFETY PRECAUTION ................................................................................ 4

8 PRE-COMMISSIONING ........................................................................................... 5

9

COMMISSIONING................................................................................................... 7

Revision HistoryRev. Revision Date Created by Checked by Approved by Description

A 15.01.2007 S. BADER M. ANDRE H. DOULAT First issueDescription latest Revision:



Legal Owner

ALSTOM PT-PE / Plants Business


PSP29A43047

Rev.

A

Date

15.01.2007

Lang.

en

Sheet

2/7© ALSTOM 2012. All rights reserved..

1 PURPOSE

This instruction serve as a base to perform commissioning tests for neutral earthingresistors. All tests described herein must be performed in de-energised and groundedconfiguration only. The site specific safety regulations shall be followed by all means.

2 AREA OF APPLICATION

It covers the field testing of neutral earthing resistors at an HV switchyard or at a powerplant.

3 REFERENCE DOCUMENTS

" Neutral earthing resistor " manufacturer service manual.

" Neutral earthing resistor " test certificate.

Plant specific single line.

Equipment specific diagram.

4 TERMINOLOGY – DEFINITION – ABBREVIATIONS

HV: High Voltage.

LV: Low Voltage.

Un: Nominal voltage.

In: Nominal current.

U0: Rated r.m.s power frequency voltage between conductor and screenor sheath for which the cable is designed

U: Rated r.m.s power frequency voltage between any two conductors forwhich the cable is designed.

Um: Maximum r.m.s power frequency voltage between any two conductors forwhich the cable is designed. It is the highest voltage that can be sustained

under normal operating conditions at any time and at any point in

the system.



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PSP29A43047

Rev.

A

Date

15.01.2007

Lang.

en

Sheet


5 LIST OF COMMISSIONING EQUIPMENTS

The following is a list of the main equipment necessary in order to carry out all the

testing of the equipment covered by this procedure.

- Warning/Caution Notices.

- Anti-personnel barriers.

- Thermometer.

- Hydrometer.

- Insulation tester 500 V - 5 kV

- Milliohmmeter

Note: All test equipment used must have a current calibration certificate traceable tointernationally accepted standards.



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Date

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Lang.

en

Sheet


6 HEALTH AND SAFETY

- The work outlined in this procedure must only be carried out by persons who arecompetent in the appropriate disciplines. These persons shall:

- Be aware of all Site Safety Procedures & Statutory Regulations and fully comply withthem.

- Recognise the hazards, which can arise when working on energised apparatus andtake all necessary precautions.

- Ensure that two people are always present when working with live equipment.

- Use approved tools and equipment.

- Wear the following safety equipment as appropriate to the area and nature of thework :

. Safety Helmet

. Safety Footwear

7 SPECIAL SAFETY PRECAUTION

Not applicable



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PSP29A43047

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en

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8 PRE-COMMISSIONING

The following section describes all tests to be carried out on neutral earthing resistor

prior to start any live integrated commissioning activities.

8.1 DATA RECORDING AND VISUAL INSPECTION

The neutral earthing resistor shall be first inspected visually. Special attention shall bepaid to any damage that could have occured during transport or installation.

8.2 RESISTOR CHECKS

Test sequence :

- Disconnect the cable and the earth link.

- Using the insulation tester set at 2.5 kV measure the insulation resistance between theresistor terminals and earth.

The minimum acceptable value is > 1k

/V with V = ref. to Uo

- Measure the value of the neutral earthing resistor using a milliohmmeter.

- Re-connect the cable and the earth link.

- Record the result on the test certificate.

8.3 CURRENT TRANSFORMERS :

The ratios and polarities of the current transformer are checked at the factory.

Perform testing of the Current Transformers following commissioning instructionGGG/00/E/TEC-------/TP/403.



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en

Sheet


8.4 EARTHING CIRCUIT CHECKS

Test sequence :

- Check the earthing circuit installation is complete.


8.5 AUXILIARY CIRCUIT CHECKS

Test sequence :

- Check and confirm the operation of the anti-condensation heaters (if applicable).

- Ensure that all bolted access covers are replaced and secured.

- Ensure that the neutral earthing cubicle is free from water / oil ingress.




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9 COMMISSIONING

The following section describes all steps to be followed in order to commission in properand methodical manner the neutral earthing resistor.


Ensure that all equipments have been restored to suitable state and ensure thatdocumentation due for permanent energisation of neutral earthing resistor, as per sitemanagement rules, is available and signed by all relevant parties.

9.2 AFTER THE ENERGISATION

Ensure that no alarm relative to neutral earthing resistor ( in stable or operating state) is

coming to the Control System.

9.3 RECORDS




Cross checkedDepartment Name Date Signature

Replaces Derived from ALSTOM Document Code

GGG/00/E/TEC-------/TP/405Responsible dept.

PEI FRCreated by

S. BaderChecked by

M. André Approved by

H. DoulatFormat

A4Legal Owner

abcdPT-PEPlant Business

Document Type


ApprovedTitle, Subtitle

Commissioning ProcedureFor HV Surge Arrester

Field Testing


PSP29A43042Rev.

ADate

15.01.2007Lang.

enSheet

1/6

Template No.: GGG/00/-/EQA---/FT/303D (released with Work Instruction GGG/00/-/EQA---/WI/306)© ALSTOM 2012. All rights reserved.

Electrical Commissioning Engineering Manual

Site Commissioning ProcedureFor HV Surge Arrester Field Testing

Table of Contents:

1

PURPOSE ................................................................................................................ 2

2 AREA OF APPLICATION .......................................................................................... 2

3 REFERENCE DOCUMENTS........................................................................................ 2

4

TERMINOLOGY – DEFINITION – ABBREVIATIONS .................................................. 2

5 LIST OF COMMISSIONING EQUIPMENTS ............................................................... 3

6

HEALTH AND SAFETY .............................................................................................. 4

7

SPECIAL SAFETY PRECAUTION ................................................................................ 4

8 PRE-COMMISSIONING ........................................................................................... 5

9

COMMISSIONING................................................................................................... 6

Revision HistoryRev. Revision Date Created by Checked by Approved by Description

A 15.01.2007 S. BADER M. ANDRE H. DOULAT First issueDescription latest Revision:



Legal Owner



PSP29A43042

Rev.

A

Date

15.01.2007

Lang.

en

Sheet

2/6 © ALSTOM 2012. All rights reserved..

1 PURPOSE

This instruction serve as a base to perform commissioning tests for HV surge arresters. All tests described herein must be performed in de-energised and groundedconfiguration only. The site specific safety regulations shall be followed by all means.

2 AREA OF APPLICATION

It covers the field testing of HV surge arresters at an HV switchyard or at a power plant.

3 REFERENCE DOCUMENTS

" HV surge arrester " manufacturer service manual.

" HV surge arrester" test certificate.

Plant specific single line / protection single line diagram.

Equipment specific diagram.

4 TERMINOLOGY – DEFINITION – ABBREVIATIONS

HV: High Voltage.

LV: Low Voltage.

Ur: Rated Voltage.

Ir: Rated Current.



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PSP29A43042

Rev.

A

Date

15.01.2007

Lang.

en

Sheet

3/6 © ALSTOM 2012. All rights reserved..

5 LIST OF COMMISSIONING EQUIPMENTS

The following is a list of the main equipment necessary in order to carry out all the

testing of the equipment covered by this procedure.

Not applicable



9 COMMISSIONING

The following section describes all steps to be followed in order to commission in properand methodical manner the HV surge arresters.


Ensure that all equipments have been restored to suitable state and ensure thatdocumentation due for permanent energisation of equipments & devices within each HVsurge arrester, as per site management rules, is available and signed by all relevantparties.

9.2 AFTER THE ENERGISATION

Just inspect visually.

9.3 RECORDS


ama00e tp001 ra site commissioning procedure for electrical systems

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