ABB RELION Series Technical Manual page 475

1MRS758755 A
REC615 and RER615
Technical Manual
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-1A2C47ED-0DCF-4225-9294-2AEC97C14D5E V1 EN
Figure 240: 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
The retrip logic provides the TRRET output, which can be used to give a retrip signal
for the main circuit breaker. Timer 1 activates the retrip logic. The operation of the
retrip logic depends on the CB fail retrip mode setting.
• The retrip logic is inactive if the CB fail retrip mode setting is set to "Off".
• If CB fail retrip mode is set to the "Current check" mode, the activation of the
retrip output TRRET depends on the CB failure mode setting.
• If CB failure mode is set to the "Current" mode, TRRET is activated when
the value of any phase current exceeds the Current value setting. The
TRRET output remains active for the time set with the Trip pulse time
setting or until all phase current values drop below the Current value
setting, whichever is longer.
• If CB failure mode is set to the "Breaker status" mode, TRRET is activated
if the circuit breaker is in the closed position. The TRRET output remains
Protection related functions
Section 5
469