P74x/EN PL/N
1, P742, P743 
(PL) 7-
 
 
Relay
English Text  Type  Source  Description 
52-B (CB open) CB Auxiliary Input (Phase B) 
52-A (CB closed) CB Auxiliary Input (phase C) 
52-B (CB open) CB Auxiliary Input (Phase C) 
Circuit Breaker closed (not (CB Aux. (52b) AND 
CB Aux. (52a))) 
Circuit Breaker is not available to trip 
Indication of discrepancy between the 52a and 
52b auxiliary contacts of the Circuit Breaker  
CB status position forced open (by default) or 
closed  
Triphase Circuit Breaker Trip from CU (Init 
50BF TBF1 / TBF2), Logical OR of : 
87BB, 50BF, Manual Trip Zone X 
Phase A Circuit Breaker Trip (Init 50BF TBF3 / 
TBF4), Logical OR of : 
O/C Protection, External Trip A, External Trip 
Phase B Circuit Breaker Trip (Init 50BF TBF3 / 
TBF4), Logical OR of : 
O/C Protection, External Trip B, External Trip 
Phase C Circuit Breaker Trip (Init 50BF TBF3 / 
TBF4), Logical OR of : 
O/C Protection, External Trip C, External Trip 
Backtrip triphase due to a trip initiation (at tBF4) 
Phase A undercurrent CBF Dead Pole Start 
Phase B undercurrent CBF Dead Pole Start 
Phase C undercurrent CBF Dead Pole Start 
Phase A overcurrent CBF Dead Pole Start 
Phase B overcurrent CBF Dead Pole Start 
Phase C overcurrent CBF Dead Pole Start 
Neutral overcurrent CBF Dead Pole Start 
Backtrip triphase due to a trip initiation from CU 
(at tBF2) 
Logical OR of ddb 121 and 270 
Valid Setting configuration 
Control Close command to the circuit breaker. 
Operates for a manual close command (menu, 
Operator trip instruction to the circuit breaker, 
via menu, or SCADA. (Does not operate for 
protection element trips) 
Manual closing order of the Circuit Breaker 
Manual Trip Order of the Circuit Breaker 
Control Close in Progress 
The relay has been given an instruction to close 
the circuit breaker, but the Manual Close timer 
Delay has not yet finished timing out 
Virtual Signal 01 from the CU to the PU via the 
fibre optic