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14.2
Line differential protection, phase
segregated (DIFL)
14. With a through load current of minimum 20% of the Ir · CTFactor, the
I
and I
are read in all phases.
Diff
Bias
The I
should be lower than 10% of the actual secondary current divid-
Diff
ed by the CTFactor, the I
surement is necessary at commissioning to guarantee that there is no
phase shift between the terminals.
15. Remove the external blocking of the trip signal when this test has
been successfully performed.
16. A complete commissioning or maintenance test requires that the
test is repeated at both terminals.
17. When the direct transfer trip is used, this function has to be tested
by activating its input, to check that trip is achieved at the remote ter-
minal. During this test, the trip circuit has to be blocked.
Testing the charging current compensation
Procedure
1.
When the tests of the differential function have been performed, set
the CCComp = On and check that the settings for XC1, XC0 and IMi-
nOpComp are correct.
2.
Check that all currents are disconnected from the terminal and con-
nect symmetrical three-phase voltages to the corresponding voltage
input.
3.
Increase the three-phase voltage to its rated 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.
Diff
Bias
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.
should be equal to this current. This mea-
Bias
U
------------------------------------------- -
=
⋅
XC1 CTFactor
Chapter 13
Verifying settings by secondary
injection
(Equation 8)
129
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