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Section 6
Testing functionality
6.4.9.5
78
4.
Apply the fault condition, including initiation of CCRBRF (50BF), 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 INITIATE input signals.
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 initiation of CCRBRF (50BF), 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.
4.
Disconnect AC and INITIATE 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.
BuTripMode = 1 out of 4
Checking the case
It is assumed that the ground-fault current setting Pickup_N is below phase current
setting Pickup_PH.
1.
Set BuTripMode = 1 out of 4.
2.
Apply the fault condition, including initiation of CCRBRF (50BF), with one-
phase current below set Pickup_PH but above Pickup_N. The residual ground-
fault should then be above set Pickup_N.
3.
Verify that back-up trip is achieved after set time. If selected, re-trip should also
appear.
4.
Disconnect AC and INITIATE input signals.
BuTripMode = 2 out of 4
Checking the case
The ground-fault current setting Pickup_N may be equal to or below phase-current
setting Pickup_PH.
1MRK 506 331-UUS A
Commissioning Manual
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