TestingDirectionalRelayElements

8/3/2019 TestingDirectionalRelayElements

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Testing Directional Relay Elements

Mike Childers, PE, Application [email protected]

Scott Schnell, PE Application [email protected]

Doble Engineering Company

PTUG 2010


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Current Polarized Element

The current polarized element uses the internal

calculated ground current and compares the phaseangle to the neutral current from a Y connectedTransformer.

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PTUG Austin Texas 2010

other and above minimum current level comparators thefault is forward.

The two current level settings are 50GFP Forward

Directional Ground Current Pickup and a0 PositiveSequence Current Restraint Factor


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Tests

The 50GFP setting / comparator can be checked by

ramping the Residual (Ground) current until the 50GFword bit asserts. The 50GF word bit is mapped to theOUT104 relay contact.


with a balanced 3 phase current and increasing one ofthe phase currents until the 32IF word bit asserts. The32IF word bit is mapped to the OUT104 relay contact.

The F32I element will assert when the ground andneutral currents are within +/- 90 degrees. The F32I wordbit is mapped to the OUT104 relay contact.


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Current Polarized Element Logic



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50GFP



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A0 Pickup



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MTA Test



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Zero-Sequence Voltage

Polarized Element

The Zero-Sequence Voltage polarized element uses the

ground current and the zero-sequence voltage. The relay calculates the Z0 impedance and compares

the result to the forward threshold value. If the


fault is forward. The threshold value is determined by theZ0F Setting.

The operation of this element is supervised by the Loss

of Potential Logic and two current level settings 50GFPForward Directional Ground Current Pickup and a0Positive Sequence Current Restraint Factor.


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Tests

The Loss of Potential logic needs to turned off during

testing. The forward threshold can be measured by applying a

phase to ground fault at the line angle and changing the


.

word bits 50GF and 32VE test need to asserted duringthe fault condition.

The F32V relay word bit is mapped to the OUT104 relay

contact. A maximum torque angle or reach test can plot the

shape of the forward threshold curve.


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Zero-Sequence Voltage

Polarized Element Logic



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Negative-Sequence Voltage

Polarized Element

The Negative-Sequence Voltage polarized element

uses the negative sequence voltage and current tocalculate the negative sequence impedance.

The relay calculates the Z2 impedance and compares


,

Z2RT. If the calculation is less than the Z2FT the fault isforward, greater than the Z2RT the fault is reverse.

The operation of this element is supervised by the Loss

of Potential Logic and two current level settings 50QFPand 50QRP Directional Ground Current Pickup and a2Positive Sequence Current Restraint Factor.


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Tests The Loss of Potential logic needs to turned off during

testing.

The R32Q relay word bit is mapped to the OUT107 relaycontact, F32Q to OUT106. Relay word bits 50QF and32QE test need to asserted during the fault condition.


The reverse threshold can be measured by applying aphase to ground fault at 180 - line angle and increasingthe I2 value until the R32Q word bit asserts. IncreasingI2 beyond 3 times Z2R deasserts R32Q. I2 greater than

Z2F asserts F32Q.

A maximum torque angle or reach test can plot theshape of the forward threshold curve.


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Negative-Sequence Voltage

Polarized Element Logic



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Questions


Documents

TestingDirectionalRelayElements