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Line differential protection (DIFL)
4.
Increase the three-phase voltage to its nominal value.
Read the values of the differential and bias currents under the
menu:
ServiceReport/DiffValues
They must correspond to the value:
IDiffL1
IDiffL2
IDiffL3
=
=
I
I
for each phase.
Bias
Diff
U
Represents measured phase voltage.
The bias currents are available under the same menu. They must
be equal to the measured differential current in each phase.
5.
Increase the measured voltage to the rated phase value and
observe the values of the differential and bias currents, pre-
sented on the terminal.
They must correspond to the following values:
IDiffL1
=
IDiffL2
=
IDiffL3
IBiasL1
IBiasL2
IBiasL3
=
=
6.
With the terminal in normal operation, not in Test mode, and
with the line energised, the I
sured under the service report menu with CCComp temporary
set to Off at both terminals. Thereafter measure the values
with the CCComp set to On.
Note! Setting CCComp to Off might cause the terminal to trip.
Therefore make sure that the trip outputs are blocked.
U
------------------------------------------- -
=
⋅
XC1 CTFactor
⋅
2 U
------------------------------------------- -
=
⋅
XC0 CTFactor
U
------------------------------------------- -
=
⋅
XC0 CTFactor
, I
and I
DiffL1
DiffL2
Chapter 11
Verifying settings by secondary
are mea-
DiffL3
injection
(Equation 8)
(Equation 9)
89
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