example_ramping_overcurrent_enu.pdf

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Testing With the RampingTest Module

Practical Example of Use


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2

Testing With the Ramping Test Module

Manual Version: Expl_RMP.AE.1 - Year 2011

OMICRON electronics. All rights reserved.

This manual is a publication of OMICRON electronics GmbH.

All rights including translation reserved.

The product information, specifications, and technical data embodied in this manual represent the technical

status at the time of writing and are subject to change without prior notice.

We have done our best to ensure that the information given in this manual is useful, accurate, up-to-date and

reliable. However, OMICRON electronics does not assume responsibility for any inaccuracies which may be

present.

The user is responsible for every application that makes use of an OMICRON product.

OMICRON electronics translates this manual from the source language English into a number of other

languages. Any translation of this manual is done for local requirements, and in the event of a dispute between

the English and a non-English version, the English version of this manual shall govern.


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OMICRON 2011 Page 3 of 21

Preface

This paper describes how to test the pick-up value of the first overcurrent element. This will be explained fordirectional or non directional relays with IDMT or DTOC tripping characteristics. It contains an applicationexample which will be used throughout the paper.

The theoretical background for testing the pick-up value of the 1stelement with the Rampingtest module will

be explained. This paper also covers the definition of the necessary Test Objectsettings as well as theHardware Configurationfor testing the 1

stelement pick-up value of directional or non-directional

overcurrent relays.

Finally the Rampingtest module is used to perform the tests which are needed for testing the pick-up valueof different protection relays:

> non-directional overcurrent protection relays

> directional overcurrent protection relays

> distance protection relays with overcurrent starter function, etc.

Supplements: Sample Control Centerfiles Example_Ramping_OvercurrentDirectional_ENU.occ andExample_Ramping_OvercurrentNonDirectional_ENU.occ (referred to in this document).

Requirements: Test Universe2.40 or later; Rampingand Control Centerlicenses.

Note: The Rampingtest module can also be used for nearly all pick-up functions for current,voltage and frequency protection etc.For testing the 1

stelement pick-up value of overcurrent protection relays the

Pick-up /Drop-off Testtab in the Overcurrenttest module can also be used.


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1 Application Example

10.5 kV

200/1

Protection functions

Overcurrent Relay

1stelement (67) / directional characteristic forward (IDMT)

2nd

element (50/51) /

non-directional characteristic (DTOC)

Figure 1: Feeder connection diagram of the application example

Parameter Name Parameter Value Notes

Frequency 50 Hz

VT (primary/secondary) 10500 V / 110 V

CT (primary/secondary) 200 A /1 A

1st

element

IEC Very Inverse Tripping characteristicDirectional Fwd Directional characteristic Forward

300 A Pick-up 1.5 x In CT primary

1.2Time multiplier setting (TD; TMS; P, etc.)(only for IDMT characteristics)

45Relay characteristic angle (only fordirectional protection function)

2nd

element

DTOC Tripping characteristic

600 A Pick-up 3 x In CT primary

100 ms Trip time delay

Table 1: Relay parameters for this example


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2 Theoretical Introduction

2.1 Define the Ramps for Testing the Pick-Up Value of the 1stElement

In this example we will use the following time and current tolerances to define the test ramps.

Parameter Name Absolute Relative

Delay time 10ms 1%

Pick-up current 10mA 3%

Drop-off / pick-up value 95%

Angle faults1)

3

1) only necessary for directional overcurrent relays

Table 2: Relay tolerances and technical data (only valid for this example)

Note: The tolerances depend on the relay type. They can be obtained from the technical specificationin the relay manual.

Fault current /AIp

200 300 700 800600500400

Very Inverse (element 1)

DTOC (element 2)

Triptime/s

1.1Ip

0.1

1

10

100

0.01

= Pick-up current tolerances of the element 1 (3%= 1.07IP 1.13IP)

= Pick-up current tolerances of the element 2 (3%)

The pick-up value of this element can only be tested with the Pulse Rampingtest module!

Figure 2: IDMT trip time characteristic from the example (Table 1)with current tolerances

Note: Some relays have an increased pick-up value for IDMT characteristics. For example, the relayused in this example has an actual pick-up value that is 1.1 times higher than the IPsetting.


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The following parameters will be tested (seeFigure 3):

1. Pick-up value of the 1stelement (measured)

2. Drop-off value of the 1stelement (measured)

3. Drop-off/pick-up value (calculated)

Faultcurrent

1st element

Test time

Drop-off

ratio

1st element

= Test current

= Measured drop-off value= Measured pick-up value

= Pick-up current tolerances (3%)

Figure 4: Time signal diagram of a pick-up/drop-off test

These three parameters can be tested with the Rampingtest module.


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2.2 Structure of the Ramping Test Module

A ramp state is defined as the stepped change of one physical quantity. Several settings can be made in thetest module.

1. With the Set modethe user can decide whether to ramp the output voltages and currents directly, orwhether to ramp calculated values such as symmetrical components, fault values or fault impedances.

2. The Signaltype and the Quantitycan be set to define the values to be ramped. It is possible to ramptwo different signals and quantities at the same time. The signals and quantities that can be chosen aredefined by the Set mode.

3. The beginning and the end of the ramps have to be defined for testing. The Delta, which is the step size,as well as the duration between two steps dtalso have to be defined. The slope d/dtis calculatedautomatically.

4. The analog outputs of the Detail Viewshow the values which are generated by the CMC test set. Thevalues displayed with a grey background are modified by the ramp and, therefore, cannot be edited in thedetail view. The remaining values can be edited freely.

Note:The analog values should be set according to realistic fault values. For example, 180 phase shiftof the currents for phase to phase faults.

5. The trigger which stops the ramp can be set in the Triggertab of the Detail View. This Stop conditionisalso displayed in the Test View. This is explained in more detail in the following section.

Note: The step duration dthas to be set according to the trigger. It must be longer than the triggertime. If the start contact is used, for instance, the step time has to be longer than the startingtime. However, if the trip command is used, then the step time has to be longer than the triptime.

If the unbalanced load protection function (negative sequence) is active, a three phase fault hasto be used for testing.

1

2

3

5

4


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Trigger conditions can be specified to control the sequence progression. They may be selected to be:

1. The test object response (e.g., start signal / trip signal)

2. A manual intervention.

The Rampingtest module includes the measurement and calculation of test values. These can be assessedautomatically and added to the report.

Note: The definition of these conditions is explained in more detail in the next chapter.

1

2

Trigger = valid ?

Start State 2


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3 Practical Introduction to Testing with the Ramping Test Module

The Rampingtest module can be found on the Start Pageof the OMICRON Test Universe. It can also beinserted into an OCC File (Control Centerdocument).

3.1 Defining the Test Object

Before testing can begin the settings of the relay to be tested must be defined. In order to do that, theTest Objecthas to be opened by double clicking the Test Objectin the OCC file or by clicking theTest Objectbutton in the test module.


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3.1.1 Device Settings

General relay settings (e.g., relay type, relay ID, substation details, CT and VT parameters) are entered inthe RIOfunction Device.

Note: The parameters V maxand I maxlimit the output of the currents and voltages to preventdamage to the device under test. These values must be adapted to the respectiveHardware Configurationwhen connecting the outputs in parallel or when using an amplifier.The user should consult the manual of the device under test to make sure that its input ratingwill not be exceeded.


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3.2 Global Hardware Configuration for Directional Overcurrent Relays

The global Hardware Configurationspecifies the general input/output configuration of the CMC test set. Itis valid for all subsequent test modules and, therefore, it has to be defined according to the relaysconnections. It can be opened by double clicking the Hardware Configurationentry in the OCC file.

3.2.1 Example Output Configuration for Protection Relays with a Secondary Nominal Current of 1 A

VN

VA

VB

VC

IA

IB

IC

IN

Note: For non-directional overcurrent relays the voltage outputs can be set to .


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3.2.2 Example Output Configuration for Protection Relays with a Secondary Nominal Current of 5 A

VN

VA

VB

VC

IB IN

IA IC

Note: Make sure that the rating of the wires is sufficient when connecting the outputs in parallel.

For non-directional overcurrent relays the voltage outputs can be set to .

The following explanations only apply to protection relays with a secondary nominal current of1 A


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3.2.3 Analog Outputs

The analog outputs, binary inputs and outputs can all be activated individually in the local HardwareConfigurationof the specific test module (see chapter3.3 ).

3.2.4 Binary Inputs

1. The start and the trip command are connected to binary inputs. BI1 BI10 can be used.

2. For wet contacts adapt the nominal voltages of the binary inputs to the voltage of the circuit breaker tripcommand or select Potential Freefor dry contacts.

3. The binary outputs and the analog inputs etc. will not be used for the following tests.

Start

Trip

1

2

3


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3.2.5 Wiring of the Test Set for Directional Overcurrent Relays

Note: The following wiring diagrams are examples only. The wiring of the analog current inputs maybe different if additional protective functions such as sensitive ground fault protection areprovided. In this case INmay be wired separately.

IN

IA

IB

IC

Protection

Relay

VA

VB

VC

Trip

(+)

(-)

Start

(+)

(-)

optional

IN

IA

IB

IC

Protection

Relay

VA

VB

VC

Trip

(+)

(-)

Start

(+)

(-)

optional

Note: For non-directional overcurrent relays the wiring of the voltage outputs is not necessary.


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3.3 Local Hardware Configuration for Directional Overcurrent Testing

The local Hardware Configurationactivates the outputs/inputs of the CMC test set for the selected testmodule. Therefore, it has to be defined for each test module separately. It can be opened by clicking theHardware Configurationbutton in the test module.

3.3.1 Analog Outputs

Note: For non-directional overcurrent relays the voltages are already deactivated in the globalHardware Configuration(see chapter3.2 ). Therefore, they will not be visible in this tab.

3.3.2 Binary Inputs


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3.4 Defining the Test Configuration

3.4.1 General Approach

Note: In this example an overcurrent relay with an IDMT tripping characteristic and an increased pick-

up value is used (seeTable 1 andFigure 2). Because of this, the nominal trip time for the pick-up current of 1.65 A is approximately 162 s. However, the start signal is not delayed which iswhy the start contact is used as the trigger.

When testing the pick-up and the drop-off values for directional or non-directional overcurrent relays, thefollowing steps are recommended.

Calculation of the Nominal Values:

For testing the pick-up and the drop-off values, the settings (Table 1)as well as the tolerances (Table 2)ofthe overcurrent protection function must be known. Also, it must be known whether there is an increasedpick-up value. From these values the nominal pick-up current, the nominal drop-off current and the absolutetolerances for these currents can be calculated. The calculations for this example are shown below:

Nominal pick-up value: 1.1 IPNominal drop-off value: 0.95 1.1 IPCurrent tolerances: 3% or 10 mA

Nominal value TOL- TOL+

Pick-up 1.65 A 49.5 mA 49.5 mA

Drop-off 1.57 A 47 mA 47 mA

Table 3: Nominal currents and tolerances for this example

Settings in the Test View:

1. As the currents are to be ramped directly, the Set modeshould be Direct.

2. In this example a phase to phase fault will be applied.

Note:If an unbalanced load protection is activated in the relay a three phase fault should be chosenbecause a phase to phase fault could trip the unbalanced load protection instead of the overcurrentprotection.

3. For the overcurrent pick-up the Magnitudeis ramped.

2 3

1

4

5 6 7


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Settings in the Detail View:

1. For directional overcurrent relays all three voltages must be set to the nominal voltage.

2. The angles of the currents have to be adapted to the fault type. For example, a phase to phase fault has180 between each fault current. For directional overcurrent relays the angles also have to be adjustedto the directional characteristic.

3. The start contact is chosen as the trigger for this test. If the trip contact is used, the step duration of theramp has to be longer than the trip time (e.g., 1.2 x Trip Time).

Settings in the Measurement view:

4. In this test the pick-up and drop-off currents are measured.

5. The pick-up value will be measured during the upward ramp. The drop-off value during the downwardramp.

6. The pick-up current will be measured when the start signal is activated. The drop-off current will bemeasured when it is deactivated.

7. The nominal values as well as the tolerances (Table 3)have to be set.

8. By dividing the measured drop-off current by the measured pick-up current, the drop-off ratio iscalculated.

9. After testing, the assessment is made automatically and the actual values, as well as the deviation fromthe nominal values, are displayed.

1

2

3

4

5 6 7

8

9


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3.5 Why it is Not Possible to Use the Ramping Test Module for the 2ndElement

For this example, the General Start signal or the General Trip signal is defined as the trigger condition fortesting the pick-up value of the 1

stelement.

For testing the 2ndelement the General Start signal cannot be used as the trigger condition because it willoperate after the threshold of the 1

stelement is exceeded. This would prevent the test current from reaching

the pick-up value of the 2nd

element (seeFigure 6).

Faultcurrent

Test time

From

To

1st

element

2nd

element

t(1stel.)

= General Trip signal= General Start signal

Figure 6: Time signal view of a ramp during an attempt to test the pick-up value of element 2

Note: The use of the Rampingtest module is only possible if the start signal of the 2nd

element iswired separately. If only a General Trip signal is available, the test will be stopped as soon asthe current of the 1

stelement is exceeded and the trip time t(1

stelement) has elapsed and,

therefore, it will fail.

To test the 2nd

element the Pulse Rampingtest module can be used instead.

Feedback regarding this application is welcome by email [email protected].
mailto:[email protected]:[email protected]:[email protected]:[email protected]


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