Woodward SEG HighPROTEC MRA4, Device Manual

Page: 414 / 510

f-Protection Module – Frequency Protection [ANSI 81O/U]
Commissioning: f< and -df/dt
Object to be tested
All frequency protection stages that are projected as f< and -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
•
Feed nominal voltage and nominal frequency to the device.
•
Decrease the frequency below the f< threshold.
•
Apply a rate of change of frequency (step change) that is below the setting value (Example apply -1 Hz
per second if the setting value is -0.8 Hz per second). After the tripping delay is expired the relay has to
trip.
Successful test result
Permissible deviations/tolerances and fallback ratios can be taken from the Technical Data.
Page 414 EN MRA4 04/09