110
Current protection Chapter 11
Verifying settings by secondary
injection
Checking the case without re-trip, RetripMode = Off
Procedure
1. Set RetripMode = Off.
2. Apply the fault condition, including start of BFP, well above the set
current value.
3. Verify that no re-trip, but back-up trip is achieved after set time.
4. Disconnect AC and start input signals.
Checking the re-trip with current check, RetripMode = I> check
Procedure
1. Set RetripMode = I> check.
2. Apply the fault condition, including start BFP, well above the set cur-
rent value.
3. Verify that retrip is achieved after set time t1 and back-up trip after
time
t2
4. Apply the fault condition, including start of BFP, with current below
set current value.
5. Verify that no re-trip, and no back-up trip is obtained.
6. Disconnect AC and start input signals.
Checking re-trip without current check, RetripMode= No I> check
Procedure
1. Set RetripMode = No I> check.
2. Apply the fault condition, including start of BFP, well above the set
current value.
3. Verify that re-trip is achieved after set time t1, and back-up trip after
time
t2.
4. Apply the fault condition, including start of BFP, 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.
6.7.5 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.
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