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1MRK 504 165-UEN Rev. K
11.5.9.6
Verifying the back-up trip mode
In the cases below it is assumed that FunctionMode = Current is selected.
Checking that back-up tripping is not achieved at normal CB tripping
Use the actual tripping modes. The case below applies to re-trip with current check.
1.
Apply the fault condition, including start of CCRBRF, with phase current well above set value
IP>.
2.
Interrupt the current, with a margin before back-up trip time, t2. It may be made at issue of re-
trip command.
3.
Check that re-trip is achieved, if selected, but no back-up trip is obtained.
The normal mode BuTripMode = 1 out of 3 should have been verified in the tests above. In
applicable cases the modes 1 out of 4 and 2 out of 4 can be checked. Choose the mode below,
which corresponds to the actual case.
Checking the case BuTripMode = 1 out of 4
It is assumed that the earth-fault current setting IN> is below phase current setting IP>.
1.
Set BuTripMode = 1 out of 4.
2.
Apply the fault condition, including start of CCRBRF, with one-phase current below set IP> but
above IN>. The residual earth-fault should then be above set IN>.
3.
Verify that back-up trip is achieved after set time. If selected, re-trip should also appear.
4.
Disconnect AC and START input signals.
Checking the case BuTripMode = 2 out of 4
The earth-fault current setting IN> may be equal to or below phase-current setting IP>.
1.
Set BuTripMode = 2 out of 4.
2.
Apply the fault condition, including start of CCRBRF, with one-phase current above set IP> and
residual (earth fault) above set IN>.
3.
Verify that back-up trip is achieved after set time. If selected, re-trip should also appear.
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
5.
Verify that back-up trip is not achieved.
6.
Disconnect AC and START input signals.
11.5.9.7
Verifying instantaneous back-up trip at CB faulty condition
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.
11.5.9.8
Verifying the case FunctionMode = CB Pos
It is assumed that re-trip without current check is selected, RetripMode = UseFunctionMode.
Transformer protection RET670
Commissioning manual
) will be above set value IN>.
0
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Section 11
Testing functionality by secondary injection
GUID-06D1545D-31F7-4B48-821E-151212962A81 v1
M12104-146 v5
M12104-150 v8
M12104-165 v6
M12104-179 v7
M12104-197 v7
173
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