1. Set RetripMode = No CBPos Check.2. Apply the fault condition, including start of CCRBRF, well above the setcurrent value.3. Verify that re-trip is achieved after the set time t1, and the back-up trip aftertime t2.4. Apply the fault condition, including start of CCRBRF, with current below setcurrent value.5. Verify that re-trip is achieved after set time t1, but no back-up trip is obtained.11.5.7.5 Verifying the back-up trip mode M12104-146 v5In the cases below it is assumed that FunctionMode = Current is selected.Checking that back-up tripping is not achieved at normal CB trippingM12104-150 v8Use 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 currentwell above set value IP>.2. Interrupt the current, with a margin before back-up trip time, t2. It may bemade 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 testsabove. 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 caseBuTripMode =1 out of 4 M12104-165 v6It is assumed that the earth-fault current setting IN> is below phase current settingIP>.1. Set BuTripMode = 1 out of 4.2. Apply the fault condition, including start of CCRBRF, with one-phase currentbelow set IP> but above IN>. The residual earth-fault should then be aboveset IN>.3. Verify that back-up trip is achieved after set time. If selected, re-trip shouldalso appear.4. Disconnect AC and START input signals.Checking the caseBuTripMode =2 out of 4 M12104-179 v7The earth-fault current setting IN> may be equal to or below phase-current settingIP>.1. Set BuTripMode = 2 out of 4.2. Apply the fault condition, including start of CCRBRF, with one-phase currentabove set IP> and residual (earth fault) above set IN>.3. Verify that back-up trip is achieved after set time. If selected, re-trip shouldalso appear.1MRK 505 378-UEN A Section 11Testing functionality by secondary injectionLine differential protection RED670 2.2 IEC 185Commissioning manual
