ABB RELION REX640 Technical Manual page 1077

1MRS759142 C
REX640
Technical Manual
CBfailuredelay Retriptime t
≥
GUID-4CAB8D81-0D15-480A-9C7B-5A2B6E1BBA09 V1 EN
t Maximum opening time for the circuit breaker
cbopen
t Maximum time for the breaker failure protection to detect the correct breaker function (the
BFP_reset
current criteria reset)
t Safety margin
margin
It is often required that the total fault clearance time is less than the given critical time.
This time often depends on the ability to maintain transient stability in case of a fault
close to a power plant.
GUID-70D5F2AF-9E29-459A-B33D-BC9972593C75 V1 EN
Figure 575: Timeline of the breaker failure protection
Timer 3
This module is activated by the CB_FAULT signal. Once activated, the timer runs
until the set CB fault delay value has elapsed. The time characteristic is according to
DT. When the operation timer has reached the maximum time value CB fault delay,
the CB_FAULT_AL output is activated. After the set time, an alarm is given so that the
circuit breaker can be repaired. A typical value is 5 s.
Retrip logic
Timer 1 activates Retrip logic, which can be used to give a retrip signal TRRET for the
main circuit breaker. The operation of Retrip logic depends on the settings CB failure
mode and CB fail retrip mode as shown in
Protection related functions
t t
+ + +
cbopen BFP reset _ margin
Table 1009.
Section 5
(Equation 257)
1071