ABB CI522A 3BSE018283R1 interface communication module
tripping coil on the circuit-breaker and a
remote tripping signal transmitted to the station at the opposite end of the line.
This first timer operates in a stand-alone
mode in the bay unit.
If the fault still persists at the end of the second time delay, the breaker failure function
uses the busbar replica to trip all the other
feeders supplying the same section of busbar
via their bay units.
A remote tripping signal can be configured in
the software to be transmitted after the first or
second timer.
Phase-segregated measurements in each bay
unit cope with evolving faults.
End fault protection
In order to protect the “dead zone” between
an open circuit-breaker and the associated
CTs, a signal derived from the breaker position and the close command is applied.
The end fault protection is enabled a certain
time after the circuit-breaker has been opened. In the event of a short circuit in the dead
zone the nearest circuit-breakers are tripped.
This function is performed in a stand-alone
mode in the bay unit.
Overcurrent function
A definite time overcurrent back-up protection
scheme can be integrated in each bay unit.
(The operation of the function, if para-meterized, may start the local breaker failure protection scheme).
This function is performed in a stand-alone
mode in the bay unit.
Current release criteria
The current release criteria is only performed
in the bay unit. It is effective for a busbar protection trip and for an intertripping signal
(including end fault and breaker failure) and
prevents those feeders from being tripped that
are conducting currents lower than the setting
of the current release criteria.
Voltage release criteria
The voltage criterion is measured in the bay
unit. The function can be configured as
release criterion per zone through internal
linking in the central unit. This necessitates
the existence of one set of voltage transformers per zone in one of the bay units. Tripping

is only possible if the voltage falls short of
(U<) or exceeds (U0>) the set value.
Additionally this release criterion can be con figured for each feeder (voltage transformers
must be installed). For details see Table 22.
Check zone criterion
The check zone algorithm can be used as a
release criterion for the zone-discriminating
low-impedance busbar protection system. It is
based on a stabilized differential current mea surement, which only acquires the feeder cur rents of the complete busbar. The isolator /
breaker positions are not relevant for this cri terion.
Neutral current detection I0
Earth fault currents in impedance-grounded
systems may be too low for the stabilized dif ferential current and phase comparison func tions to detect. A function for detecting the
neutral current is therefore also available, but
only for single phase-to-earth faults.
Pole discrepancy
A pole discrepancy protection algorithm
supervises that all three poles of a circuit breakers open within a given time.
This function monitors the discrepancy bet ween the three-phase currents of the circuit breaker.
When it picks up, the function does not send
an intertripping signal to the central unit, but, if
configured, it starts the local breaker failure
protection (BFP logic 3).
This function is also performed in a stand alone mode in the bay unit.
Event recording
The events are recorded in each bay unit. A
time stamp with a resolution of 1ms is attach ed to every binary event. Events are divided
into the three following groups:
• system events
• protection events
• test events
The events are stored locally in the bay unit or
in the central unit.
Disturbance recording
This function registers the currents and the
binary inputs and outputs in each bay. Volt ages can also be optionally registered (seeTable 14).