Siemens 7UT51 Instruction Manual page 88

6
Bus Differential Protection (87B)
Bus Differential Protection (87B) Occurrence
Trip and Reset
Any 87B trip event will also cause event 5671 to occur. With the
default marshalling, event 5671 will actuate all the trip contacts,
signal contact 2, and (as for the general trip of any protection
function) signal contact 1. Outputs actuated by 87B trip events will
remain actuated until the 87B function resets (the same conditions
for dropout, event 5631G), plus the additional reset time
(Address 1827).
The 87B function will trip if and when ALL the following are true:
• an 87B pickup has occurred, and it has not yet dropped out or
already caused a trip,
- -
• the 87B time before
• any restraint has ended,
There are separate 87B trip events for each phase, and one (event
5691) that reports the 87B trip of any phase. With the default
marshalling, event 5691 will light and latch LED 2 and (as for any
protection function trip event) LED 1.
If an 87B trip event occurs, the values of the differential currents
and restraining currents for each phase at the time of the trip are
recorded in the then open fault log.
Configuration Events
-
If the bus description settings are changed, the current
factors for the phase currents are recalculated and reported.
Table 6.1 Events Related to Differential Protection of a Bus (87B)
88
trip time delay (if there is one) has expired,
LCD Abbreviation
87Diff GenTrip
87Diff TripPhA
87Diff TripPhB
87Diff TripPhC
87 Trip
Diff Ia= value
Diff Ib= value
Diff Ic= value
Rest Ia= value
Rest Ib= value
Rest Ic= value
-
matching k CT 1= factor
k CT 2= factor
k CT 3= factor
7UT51 v3
Event Oper Fault In/Out
5671 C G
5672 C
5673
C
5674
C
5691
C
5701 C
5702
C
5703
C
5704
C
5705
C
5706
C
5713 C
5714
C
5715
C
PRIM-2330C
S T
S T
S T
S T
S T