Protective Elements
Commissioning: df/dt - ROCOF
Object to be tested
All frequency protection stages that are projected as df/dt.
Necessary means
Three-phase voltage source and
Frequency generator that can generate and measure a linear, defined rate of change of frequency.
Procedure
Testing the threshold values
Keep on increasing the rate of change of frequency until the respective element is activated.
Note the value.
Testing the trip delay
Set the test voltage to nominal frequency.
Now apply a step change (sudden change) that is 1.5 times the setting value (example: apply 3 Hz per
second if the setting value is 2 Hz per second) and
Measure the tripping time at the relay output. Compare the measured tripping time to the configured tripping
time.
Successful test result:
Permissible deviations/tolerances and dropout ratios can be taken from the Technical Data.
923 MCDGV4 DOK-HB-MCDGV4-2E
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