4. Apply the fault condition, including start of CCRBRF, with at least one-phase
current below set IP> and residual (earth fault) above set IN>. The current
may be arranged by feeding three- (or two-) phase currents with equal phase
angle (I0-component) below IP>, but of such value that the residual (earth
fault) current (3I
0
) will be above set value IN>.
5. V
erify that back-up trip is not achieved.
6. Disconnect AC and START input signals.
11.5.7.6 Verifying instantaneous back-up trip at CB faulty condition
M12104-197 v7
Applies in a case where a signal from CB supervision function regarding CB being
faulty and unable to trip is connected to input CBFLT.
1. Repeat the check of back-up trip time. Disconnect current and START input
signals.
2. Activate the input CBFLT. The output CBALARM (CB faulty alarm) should
appear after set time tCBAlarm. Keep the input activated.
3. Apply the fault condition, including start of CCRBRF, with current above set
current value.
4. Verify that back-up trip is obtained without intentional delay, for example
within 20ms from application of start.
11.5.7.7 Verifying the function mode
Current/Contact
M12104-237 v6
To be made only when FunctionMode = Current/Contact is selected. It is suggested
to make the tests in one phase only, or at three-phase trip applications for just three-
phase tripping.
Checking the case with fault current above set value
IP>
M12104-241 v7
The operation shall be as in FunctionMode = Current.
1. Set FunctionMode = Current/Contact.
2. Leave the inputs for CB close inactivated. These signals should not influence.
3. Apply the fault condition, including the start of CCRBRF, with the current
above the set IP> value.
4. Check that the re-trip, if selected, and back-up trip commands are achieved.
Checking the case with fault current below set value
I>BlkCont
M12104-281 v10
It simulates a case where the fault current is very low and operation will depend on
CB position signal from CB auxiliary contact. It is suggested that re-trip without
current check is used, setting RetripMode = No CBPos Check.
1. Set FunctionMode = Current/Contact.
2. Apply input signal for CB closed to the relevant input or inputs CBCLDL1 (2
or 3).
3. Apply the fault condition with input signal(s) for start of CCRBRF. The value
of current should be below the set value I>BlkCont.
Section 11 1MRK 505 378-UEN A
Testing functionality by secondary injection
186 Line differential protection RED670 2.2 IEC
Commissioning manual
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