CCBRBRF can be blocked by using an internally assigned signal or an external signal
from a binary input. This signal blocks the function of the breaker failure protection
even when the timers have started or the timers are reset.
The retrip timer is initiated after the start input is set to true. When the pre-defined
time setting is exceeded, CCBRBRF issues the retrip and sends a trip command, for
example, to the circuit breaker's second trip coil. Both a retrip with current check
and an unconditional retrip are available. When a retrip with current check is chosen,
the retrip is performed only if there is a current flow through the circuit breaker.
The backup trip timer is also initiated at the same time as the retrip timer. If
CCBRBRF detects a failure in tripping the fault within the set backup delay time,
which is longer than the retrip time, it sends a backup trip signal to the chosen
backup breakers. The circuit breakers are normally upstream breakers which feed
fault current to a faulty feeder.
The backup trip always includes a current check criterion. This means that the
criterion for a breaker failure is that there is a current flow through the circuit
breaker after the set backup delay time.
REF 615
REF 615
REF 615
REF 615
Figure 427: Typical breaker failure protection scheme in distribution substations
5.2.6
Signals
Table 775: CCBRBRF Input signals
Name
Type
Default
Description
I_A
SIGNAL
0
Phase A current
I_B
SIGNAL
0
Phase B current
I_C
SIGNAL
0
Phase C current
Table continues on the next page
1MRS757644 H
Protection related functions
620 series
Technical Manual
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