4.
Apply the fault condition, including start of CCRBRF, 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 START input signals.
6.4.6.5
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 start of CCRBRF, with phase current
well above set value
IP
.
2.
Arrange switching the current off, 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.
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>
. It can be obtained by
applying a single-phase current.
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
Section 6
1MRK 504 126-UEN -
Testing functionality
52
Commissioning Manual