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Definite and inverse time-delayed
residual overcurrent protection (TEF)
65°
Iset
Figure 8: Measuring characteristic of the directional element.
6.
To activate the directional function, set Direction = Direction-
al.
7.
Set the polarising voltage to 2% of U
tween voltage and current to 65°.
8.
Check the operate current of the IMin function.
The function activates the TEF--START output.
9.
When independent time delay (definite) is selected, check the
operate time of the t1 timer by injecting a current two times
the set IMin operate value.
When inverse time delay is selected, check the operate time at
three points of the inverse characteristic. The formulas for operate
time for different types of inverse time delay curves are shown in
table 5.
Verifying settings by secondary
Upol = -3U
ϕ
IN Operation
and the phase angle be-
b
Chapter 10
injection
0
99000052.vsd
67
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