f-Protection Module – Frequency [81O/U, 78, 81R]
Commissioning: Frequency Protection (Overfrequency) [ANSI 81O]
Object to be tested
All parameterized overfrequency protection stages.
Necessary means
•
Three-phase voltage source with variable frequency.
•
Timer
Procedure
Testing the threshold values
•
Keep on increasing the frequency until the respective frequency element is activated
•
Note the frequency value.
•
Disconnect the test voltage.
Testing the trip delay
•
Set the test voltage to nominal frequency.
•
Now connect a frequency jump (activation value) and then start a timer. Measure the tripping time at the
relay output.
Testing the fallback ratio
Reduce the measuring quantity to less than 99.95% of the trip value (or 0.05% fn). The relay must only fall back
at 99.95% of the trip value at the earliest (or 0.05% fn).
Successful test result
Permissible deviations/tolerances can be taken from the Technical Data.
Commissioning: Frequency Protection (Underfrequency) [ANSI 81U]
For all parameterized underfrequency elements, this test can be carried out similar to the test for overfrequency
protection (by using the related underfrequency values).
Please consider the following deviations:
•
For testing the threshold values the frequency has to be decreased until the protection element is
activated.
•
For detection of the fallback ratio the measuring quantity has to be increased to more than 100.05% of
the trip value (or 0.05% fn). At 100.05% of the trip value the relay is to fall back at the earliest
(or 0.05% fn).
EN MRU4 10/09
Page 265
