GE Multilin DFF Instruction Manual page 42

7.14 FREQUENCY UNITS CHECKS.
1. Absolute threshold checks
Configure the frequency units as "FREQ" with the following settings:
Unit 1 : 49 Hz
Unit 2 : 48 Hz
Unit 3 : 47 Hz
Unit 4 : 46 Hz
Unit 5 : 45 Hz
Unit 6 : 44 Hz
Unit 7 : 43 Hz
Unit 8 : 42 Hz
Decrease the frequency gradually and check that each unit has an error margin not higher than 0.01 Hz.
2. Rate of change of Frequency checking.
Configure the frequency units as "df / dt" with the following settings:
Unit 1 : - 0.1 Hz/s
Unit 2 : - 0.2 Hz/s
Unit 3 : - 0.5 Hz/s
Unit 4 : - 1 Hz/s
Unit 5 : - 1.5 Hz/s
Unit 6 : - 2 Hz/s
Unit 7 : - 5 Hz/s
Unit 8 : - 10 Hz/s
Set all units to the same frequency supervision level.
Test each Frequency Unit simulating frequency variations, decreasing ramps, with rates of change of frequency more
negative than the setting of the unit under test. Check that each unit operates with an error margin not higher than
0.05 Hz/s.
GEK-106166E
ACCEPTANCE TESTS
DFF Digital Feeder Relay 41