scheider electric MiCOM P746, Technical Manual

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Commissioning and Maintenance P746/EN CM/F21
MiCOM P746 (CM) 10-27
6.2.3.2 External initiation of BF Protection
P
rotective
Relays
P746
Busbar
protection
Trip A, B, C
P3752ENc
Trip Command
To test the retrip:
As shown in the above figure, we initiate the opto inputs “External Trip A,B,C” and apply a
current twice the I< threshold.
Check that the P746 issues a retrip order after the settable time tBF3.
IMPORTANT: THE TIME INDICATED ON THE LCD IS THE DURATION OF THE
OPERATION OF THIS TRIP COMMAND.
The fast reset retrip order is equal to the fault clearance time + 13ms – tBF3 pick-up time.
For example if tBF3 = 50ms and the fault is cleared after 60ms, the P746 displayed value will
be 23ms.
To test the backtrip:
Do the same tests as for retrip however apply a faulty current for more than tBF4 and check
that the backtrip signal is sent.
Check that feeder 1 and feeder 2 connected to the bus-section 1 are tripped.
CM
6.2.3.3 CB unavailable:
Feeder 1 Feeder 2 Coupler Feeder 3 Feeder 4
P3753ENb
Zone 1 Zone 2
Apply an internal fault in zone 2 and energise the opto input “CB unavailable” of the coupler
and check that both bus-sections are tripped simultaneously.
Note: If the input “CB unavailable” is energised, the CB will be not tripped
and is normally used only for bus-coupler.
The backtrip order is equal to (the maximum between the fault clearance time and 250 ms) –
tBF4 pick-up time.
For example if tBF4 = 200ms and the fault is cleared before 450ms, the P746 will display
450ms.