f-Protection Module – Frequency [81O/U, 78, 81R]
Commissioning: df/dt
Object to be tested
All frequency protection stages that are projected as df/dt.
Necessary means
•
Three-phase voltage source.
•
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).
•
Measure the tripping time at the relay output. Compare the measured tripping time to the parameterized.
Successful test result
Permissible deviations/tolerances and fallback ratios can be taken from the Technical Data.
Page 266
EN MRU4 10/09
