1. Apply the fault condition, including start of CCRBRF, 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 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>.
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 may
be arranged by feeding three- (or two-) phase currents with equal phase angle
(I0-component) below IP>, but of such value that the residual (earth fault)
current (3I
0
) will be above set value IN>.
5. Verify that back-up trip is not achieved.
6. Disconnect AC and START input signals.
6.5.5.6 Verifying the case
RetripMode
=
Contact
It is assumed that re-trip without current check is selected, RetripMode = Contact.
1MRK 502 049-UEN A Section 6
Testing functionality
71
Commissioning manual