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Secondary system supervision Chapter 11
Verifying settings by secondary
injection
10.2.4 Checking the operation of the du/dt and di/dt based function
Check the operation of the du/dt and di/dt based function, if included in the IED.
Procedure
1. Simulate normal operating conditions with the three-phase currents
in phase with their corresponding phase voltages and with all of
them equal to their rated values.
2. Connect the nominal dc voltage to the CBCLOSED binary input.
3. Change the voltages and currents in all three phases simultaneous-
ly.
The voltage change should be greater then set DU> and the current
change should be less than the set DI<.
• The BLKU and BLKZ signals appear without any time delay. The
BLKZ signal will be activated , only if the internal deadline detection
is not activated at the same time.
• 3PH should appear after 5 seconds, if the remaining voltage levels
are lower than the set UDLD< of the DLD function.
4. Apply normal conditions as in step 1.
The BLKU, BLKZ and 3PH signals should reset, if activated, see step 3.
5. Change the voltages and currents in all three phases simultaneous-
ly.
The voltage change should be greater then set DU> and the current
change should be greater then the set DI<.
The BLKU, BLKZ and 3PH signals should not appear.
6. Disconnect the dc voltage to the CBCLOSED binary input.
7. Apply normal conditions as in step 1.
8. Repeat step 3.
9. Connect the nominal voltages in all three phases and feed a current
below the operate level in all three phases.
10. Keep the current constant. Disconnect the voltage in all three phas-
es simultaneously.
The BLKU, BLKZ and 3PH signals should not appear.
10.2.5 Completing the test
Continue to test another function or complete the test by setting the test mode to off.
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