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14.1
Line differential protection, phase
segregated (DIFL)
I
+
I
Local
Remote
I
=
------------------------------------------ -
Bias
2
(
)
{
[
(
I
=
Max
I
Bias
Bias
Evaluate
The test is performed by injecting a single and a symmetrical three-phase current. If the optional
charging current compensation function is included, the CCComp shall be Off and no measuring
voltage connected to the terminal.
Testing the line differential protection
Procedure
1.
Block the trip signal.
The blocking can not be done by the COMBITEST test switch. It has to
be made on the station side of the test switch.
2.
Set the protection in test mode from the HMI unit.
The TestMode is found in the menu under:
Test/TestMode/Operation
The TestMode command must be saved in order to be activated. When
the protection is equipped with COMBITEST test switch, the test mode
is automatically activated but not saved when the test handle is inserted.
3.
Prepare the terminal for verification of settings as outlined in section
"Prepare for test" in this chapter.
4.
Set the Disturbance report to Off.
This command is found in the menu under:
Test/TestMode/DisturbReport
5.
Activate the trip by setting Release local.
This command is found in the menu under:
Test/TestMode/Differential
This command must be saved in order to be activated. Observe that the
command ReleaseLocal will allow the trip outputs to be activated during
the tests.
)
] OR
[
⋅
(
0.5
I
Bias
Own phase
Verifying settings by secondary
)
]
}
Other phases
Chapter 13
injection
(Equation 6)
(Equation 7)
127
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