1. Apply the fault condition, including BFI_3P of CCRBRF (50BF), with a current
below set Pickup_PH.
2. Repeat the fault condition and increase the current in steps until a trip occurs.
3. Compare the result with the set Pickup_PH.
4. Disconnect AC and BFI_3P input signals.
If No CBPos Check or Retrip off is set, only back-up trip can be used to
check set IP>.
11.5.8.2 Checking the residual (ground fault) current trip value
Pickup_N
set below
Pickup_PH
Check the low set Pickup_N current where setting FunctionMode = Current and setting
BuTripMode = 1 out of 4
1. Apply the fault condition, including BFI_3P of CCRBRF (50BF), with a current just
below set Pickup_N.
2. Repeat the fault condition and increase the current in steps until trip appears.
3. Compare the result with the set Pickup_N.
4. Disconnect AC and BFI_3P input signals.
11.5.8.3 Checking the re-trip and back-up times
The check of the set times can be made in connection with the check of trip values above.
Choose the applicable function and trip mode, such as FunctionMode = Current and
RetripMode = CB Pos Check .
1. Apply the fault condition, including initiation of CCRBRF (50BF), well above the
set current value. Measure time from BFI_3P of CCRBRF (50BF).
2. Check the re-trip t1 and back-up trip times t2 and t3.
In applicable cases, the back-up trip for multi-phase pickupt2MPh and back-up trip
2, t2 and t3 can also be checked. To check t2MPh, a two-phase or three-phase
initiation shall be applied.
3. Disconnect AC and BFI_3P input signals.
11.5.8.4 Verifying the re-trip mode
Choose the mode below, which corresponds to the actual case.
In the cases below it is assumed that FunctionMode = Current is selected.
Section 11 1MRK 504 165-UUS -
Testing functionality by secondary injection
192 Transformer protection RET670 2.2 ANSI
Commissioning manual
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