66
Definite and inverse time-delayed
residual overcurrent protection (TEF)
Chapter 10
Verifying settings by secondary
injection
5 Definite and inverse time-delayed residual
overcurrent protection (TEF)
Prepare the terminal for verification of settings as outlined in section “Preparing for
test” in this chapter.
Normally, the test of the earth-fault overcurrent protection is made in conjunction with
the testing of the distance protection functions, using the same multiphase test-set. Ob-
serve that the polarising voltage is equal to 3Uo.
5.1 Checking the operate values of the
current measuring elements
Procedure
1. Set the logical input signals to logical 0 and note on the local
HMI that the TEF--TRIP and the TEF--TRSOTF signal is not ac-
tivated (= logical 0).
Values of the logical signals belonging to the time delayed residual
overcurrent protection are available under menu tree:
ServiceReport/Functions/EarthFault/TimeDelayEF
2. Set the polarising voltage to 2% of U
b
and the phase angle be-
tween voltage and current to 65°, the current lagging the volt-
age.
3. Check that the operate current of the forward directional ele-
ment is equal to the IN> Dir setting.
The IN> Dir function activates the TEF--STFW output.
4. Check with angles ϕ = 20° and 110° that the measuring ele-
ment operates when 3I
0
cos (65° - ϕ) >= IN> Dir.
5. Reverse the polarising voltage (ϕ = 180° + 65° = 245°) and
check that the operate current of the reverse directional ele-
ment is 0.6 · IN> Dir.
The function activates the TEF--STRV output.
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