x/EN PL/Na7 
 
 7-
 
MiCOM P74
 
 
Relay 
English Text  Type  Source  Description 
Virtual Signal 16 from the CU to the PU via the 
fibre optic 
Fibre optic Maximum primary current encoding 
exceeded 
Fault in the dead zone on the neutral 
Fault in the dead zone on a phase 
Variation detected on phase A (not used) 
Variation detected on phase B (not used) 
Variation detected on phase C (not used) 
Variation detected on the neutral (not used) 
Signal 
protection) 
Allows external protection to initiate breaker fail 
PSL (50BF Backtrip 
protection) 
50BF Backtrip order from an other protection 
Retrip of phase A due to an external trip 
initiation of this phase (at tBF3) 
Retrip of phase B due to an external trip 
initiation of this phase (at tBF3) 
Retrip of phase C due to an external trip 
initiation of this phase (at tBF3) 
Signal 
protection) 
Allows external protection to initiate breaker fail 
Signal 
protection) 
Allows external protection to initiate breaker fail 
Signal 
protection) 
Allows external protection to initiate breaker fail 
Trigger for the Fault Recorder 
Fibre communication to the CU error 
Warning: fibre communication to be changed 
48V Field Voltage Failure 
When the forced positions of the CB and the 
Isolators are used (during commissioning test) 
1st Stage Overcurrent Start A  
1st Stage Overcurrent Start B 
1st Stage Overcurrent Start C 
Blocking of the 1
st
 stage overcurrent time delay  
1st Stage Overcurrent Trip 3 phase 
Fast external phase fault criterion to block the 
connected zone enabled 
2nd Stage Overcurrent Start A  
2nd Stage Overcurrent Start B  
2nd Stage Overcurrent Start C 
Blocking of the 1
st
 stage overcurrent time delay  
2nd Stage Overcurrent Trip 3 phase 
Local overcurrent phase A to block the 87BB on 
external fault 
Local overcurrent phase B to block the 87BB on 
external fault 
Local overcurrent phase C to block the 87BB 
on external fault 
Overcurrent Local trip confirmation 
Local overcurrent phase A Trip confirmation for 
87BB or 50BF (CU) trip order  
Local overcurrent phase B Trip confirmation for 
87BB or 50BF (CU) trip order