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.
6.3.9.5 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 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.
Checking the case
BuTripMode
=
1 out of 4
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.
Checking the case
BuTripMode
=
2 out of 4
The ground-fault current setting Pickup_N may be equal to or below phase-current setting
Pickup_PH.
Section 6 1MRK 505 293-UUS A
Testing functionality
62
Commissioning manual
To Next Page
Loading...
Need help?
General
