4. Apply the fault condition, including initiation of CCRBRF (50BF), with currentbelow 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.6.3.9.5 Verifying the back-up trip modeIn the cases below it is assumed that FunctionMode = Current is selected.Checking that back-up tripping is not achieved at normal CB trippingUse 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 phasecurrent well above set value IP.2. Interrupt the current, with a margin before back-up trip time, t2. It may be made atissue 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 modebelow, which corresponds to the actual case.Checking the caseBuTripMode =1 out of 4It is assumed that the ground-fault current setting Pickup_N is below phase current settingPickup_PH.1. Set BuTripMode = 1 out of 4.2. Apply the fault condition, including initiation of CCRBRF (50BF), with one-phasecurrent below set Pickup_PH but above Pickup_N. The residual ground-fault shouldthen be above set Pickup_N.3. Verify that back-up trip is achieved after set time. If selected, re-trip should alsoappear.4. Disconnect AC and INITIATE input signals.Checking the caseBuTripMode =2 out of 4The ground-fault current setting Pickup_N may be equal to or below phase-current settingPickup_PH.Section 6 1MRK 505 293-UUS ATesting functionality62Commissioning manual
