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Section 11
Testing functionality by secondary injection
Test points
P1
P2
P3
P4
Change the magnitude and angle of phase-to-phase voltage to achieve impedances at test points
P1, P2, P3 and P4. For each test point, observe that the output signals, START and STZx are
activated (where x is 2 or 3 depending on selected zone). After the operate time delay of the
respective zone has elapsed, also the signals TRIP and TRZx (where x is 2 or 3 depending on
selected zone) shall be activated.
Load encroachment
Load encroachment operates on the same measuring principles as the impedance measuring zones.
Thus, it is necessary to follow the same principles as for distance protection when performing the
secondary injection tests. Measure operating characteristics during constant current conditions. Keep
the injected current as close as possible to the rated value of its associated input transformer or
lower. Ensure, however, that it is higher than 30% of the rated current. Ensure that the maximum
continuous current of an IED does not exceed four times Its rated value, if the measurement of the
operating characteristics runs under constant voltage conditions.
Measuring the operate limit of set values of load encroachment function
The load encroachment does not have any special output to be verified. It can only be verified with
the distance START and TRIP outputs.
Steps to test the load encroachment:
1.
Supply the IED with healthy conditions for at least two seconds.
2.
Apply the fault condition and slowly decrease the injected impedance to find the operate value
for of the phase-to-earth and phase-to-phase loops.
Under voltage seal-in
The under voltage seal-in logic can be verified using the TRUV and STUV outputs.
Steps to verify the logic:
1.
Keep all the current and voltage in normal balanced condition.
2.
Keeping the phase current at rated value, slowly reduce the voltage till it enters into the
respective zone mho characteristics and also below the set value of the under voltage seal-in
logic.
3.
Before the operate time delay of the respective zone, reduce the current magnitude so that the
operating impedance moves out of the mho characteristics.
4.
The under voltage seal-in should give a START and TRIP after the operate time delay is set for
the under voltage logic.
11.4.16.2
Completing the test
Continue to test another function or end the testing by setting the parameter TestMode to Off under
Main menu /Tests /IED test mode /1: TESTMODE . If another function is tested, then set the
parameter Blocked to No under Main menu /Tests /Function test modes /Impedance /
ZGVPDIS /1: ZGVPDIS for the function, or for each individual function in a chain, to be tested next.
Remember to set the parameter Blocked to Yes, for each individual function that has been tested.
158
X
ZxFwd · sin(LineAngle)
((ZxFwd -ZxRev / 2) · sin(LineAngle))
((ZxFwd -ZxRev / 2) · sin(LineAngle))
-ZxRev · sin(LineAngle)
© 2017 - 2022 Hitachi Energy. All rights reserved
1MRK 504 165-UEN Rev. K
R
ZxFwd · cos(LineAngle)
ZxFwd / 2 · (1 + cos(LineAngle) + ZxRev/2 · (1
– cos(LineAngle))
-ZxFwd / 2 · (1 – cos(LineAngle) + ZxRev / 2 ·
(1 + cos(LineAngle))
-ZxRev · cos(LineAngle)
GUID-4E0958A9-000E-440F-A880-89B54774AC63 v3
GUID-1219D2CC-D2EC-44B1-8F2E-A4C292590680 v2
GUID-93110921-550A-441F-A36F-901488CC41BB v3
Transformer protection RET670
Commissioning manual
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