15.7.6.3 Completing the test
Continue to test another function or end the test by changing the Test mode setting
to Off. Restore connections and settings to their original values, if they were
changed for testing purposes.
15.8 Frequency protection
15.8.1 Underfrequency protection SAPTUF
Prepare the IED for verification of settings outlined in section "Overview" and
section "Preparing for test" in this chapter.
15.8.1.1 Verifying the settings
Verification of START value and time delay to operate
1. Check that the IED settings are appropriate, especially the START value and
the definite time delay.
2. Supply the IED 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. Check 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
1. The test above can be repeated to check the time to reset.
2. The tests above can be repeated to test the frequency dependent inverse time
characteristic.
Verification of the low voltage magnitude blocking
1. Check that the IED settings are appropriate, especially the StartFrequency,
IntBlockLevel, and the TimeDlyOperate.
2. Supply the IED 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
IntBlockLevel.
1MRK 502 029-UEN A Section 15
Verifying settings by secondary injection
201
Installation and commissioning manual
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