GE Multilin 750/760 Feeder Management Relay 5-71
5 SETPOINTS 5.6 S5 PROTECTION
5
5.6.9 BREAKER FAILURE
PATH: SETPOINTS ÖØ S5 PROTECTION ÖØ BRKR FAILURE
Breaker failure monitors the phase currents while a trip command exists. If any phase current is above the set level after the
BRKR FAILURE DELAY time expires, a breaker failure will be declared, which will operate the selected output relays and force
the 750/760 autoreclose scheme to lockout.
To provide user flexibility, the 750/760 has included two programmable delays for the breaker failure function. The timers
can be used singularly or in combination with each other. The difference between the two is their location in the logic dia-
gram.
BRKR FAILURE DELAY 1 starts counting down from the user programmed delay setpoint once a Trip condition is recog-
nized. On the other hand, BRKR FAILURE DELAY 2 provides a delay where it does not begin counting down until a trip
condition is present, Delay 1 has expired, and one of the phase currents is above the BRKR FAILURE CURRENT setpoint. If
one of the delays is not required, simply program the unwanted timer to its minimum value.
The operation of the filter that reduces the overreaching effect of asymmetrical offset currents will cause the mea-
sured current to ramp down to zero after the breaker trips. It is strongly recommended that a margin of at least 1.5
power frequency cycles be added to the expected breaker time-to-trip for the
BRKR FAILURE DELAY 1 and BRKR FAIL-
URE DELAY 2 setpoints.
Figure 5–34: BREAKER FAILURE LOGIC
îš„ BRKR FAILURE
îš„ [ENTER] for more
BRKR FAILURE
FUNCTION: Disabled
Range: Disabled, Trip, Alarm, Latched Alarm, Control
BRKR FAILURE
RELAYS (3-7): -----
Range: Any combination of 3 to 7 Auxiliary relays
See 5.6.1: Overview on page 5–32 for details.
BRKR FAILURE
DELAY 1: 0.10 s
Range: 0.03 to 1.00 s in steps of 0.01
BRKR FAILURE
DELAY 2: 0.00 s
Range: 0.03 to 1.00 s in steps of 0.01
BRKR FAILURE
CURRENT: 1.00 x CT
Range: 0.05 to 20.00 x CT in steps of 0.01
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NOTE
Courtesy of NationalSwitchgear.com
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