busbar protection operation or individual bay breaker failure protection operation.
Breaker failure protection can be internal or external to the IED.
By a parameter setting it is possible to provide self-rest or latched trip output contacts
from the IED. However it shall be noted that the latching is electrical (that is, if DC
supply to the IED is lost the output contacts will reset).
However, sometimes due to a lar
ge number of required trip output contacts (that is,
single pole operated circuit breakers and/or main and backup trip coils), a separate trip
repeat relay unit is applied for the tripping of the circuit breakers in the station. In that
case the tripping arrangement can be done in different ways.
SEMOD130408-6 v4
Trip arrangement with one-phase version
When one-phase version of the IED is used it is typically required to have three IEDs
(that is, one per phase). Thus, when busbar protection in one IED operates the trip
commands will be given to all bays but internal circuit breaker failure function will be
started in the same phase only. In order to secure internal breaker failure picking-up in
all three phases it is advisable to do the following. Connect a zone, say Zone A, trip
signal from one IED to the external trip input of the Zone A in the other two IEDs.
Thus all three IEDs will then issue trip in Zone A and pick-up internally circuit breaker
failure protection in all three phases.
Note that:
• similar arrangements shall be done for the other zones
• this have to be done between all three IEDs (that is, three times)
Such a scheme can be arranged in one of the following ways:
• by wiring between three IEDs
• by using GOOSE messages when IEC 61850-8-1 is used
• by using LDCM communication module.
Note that in this case the external trip signal from other two IEDs shall be arranged via
pulse timer in configuration in order to avoid locking of the trip signal between three
IED. Such arrangement via GOOSE is given in Figure
53:
1MRK 505 370-UUS A Section 6
Differential protection
Busbar protection REB670 2.2 ANSI 133
Application manual
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