ABB REL670 - Frequency Protection; Underfrequency Protection (PTUF, 81)

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Frequency protection Chapter 11
Verifying settings by secondary
injection
8 Frequency protection
8.1 Underfrequency protection (PTUF, 81)
Prepare the terminal for verification of settings as outlined in section 2 "Preparing for test" in
this chapter.
8.1.1 Verifying the settings
Verification of Start-value and time delay to operate
Procedure
1. Make sure that the IED settings are appropriate, especially the
Start-value and the definite time delay.
2. Supply the terminal with three-phase voltages at their rated values.
3. Slowly decrease the frequency of the applied voltage, until the
START signal appears.
4. Note the operate value and compare it with the set value.
5. Increase the frequency until rated operating levels are reached.
6. Make sure that the START signal resets.
7. Instantaneously decrease the frequency of the applied voltage to a
value about 20% lower than the operate value.
8. Measure the time delay of the TRIP signal, and compare it with the
set value.
Extended testing
Procedure
1. The test above can be repeated to check the time to reset.
2. The tests above can be repeated to test the voltage dependent in-
verse time characteristic.
Verification of the low voltage magnitude blocking
Procedure
1. Make sure that the IED settings are appropriate, especially the Start-
Frequency
, IntBlkStVal, and the tTrip.
2. Supply the terminal with three-phase voltages at rated values.
3. Slowly decrease the magnitude of the applied voltage, until the
BLKDMAGN signal appears.
4. Note the voltage magnitude value and compare it with the set value,
IntBlkStVal.