Verifying Instantaneous Back-Up Trip At Cb Faulty Condition - ABB RET650 2.1 IEC Commissioning Manual

1MRK 504 160-UEN -
10.4.6.6
Transformer protection RET650 2.1 IEC
Commissioning manual
Testing functionality by secondary injection
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.
BuTripMode = 1 out of 4
Checking the case
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.
BuTripMode = 2 out of 4
Checking the case
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 ) will be above set value IN>.
0
5. Verify that back-up trip is not achieved.
6. Disconnect AC and START input signals.

Verifying instantaneous back-up trip at CB faulty condition

Applies in a case where a signal from CB supervision function regarding CB being
faulty and unable to trip is connected to input CBFLT.
1. Repeat the check of back-up trip time. Disconnect current and START input
signals.
2. Activate the input CBFLT. The output CBALARM (CB faulty alarm) should
appear after set time tCBAlarm. Keep the input activated.
3. Apply the fault condition, including start of CCRBRF, with current above set
current value.
4. Verify that back-up trip is obtained without intentional delay, for example
within 20ms from application of start.
Section 10
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