4. Apply the fault condition, including start of CCRBRF, with current below set
current value.
5. Verify that re-trip is achieved after set time t1, but no back-up trip is obtained.
6. Disconnect AC and START input signals.
6.4.6.5 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. Arrange switching the current off, 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.
4. Disconnect AC and START input signals.
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>. It can be obtained by
applying a single-phase current.
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
Section 6 1MRK 504 126-UEN -
Testing functionality
52
Commissioning Manual
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