2-24
Specifications
Date Code 20010515
SEL-2BFR, -2/BFR Instruction Manual
When you set DRTE equal to N, Relay Word bit TA asserts immediately when the TRIP A input
is asserted, regardless of the A-phase current measured.
DWG: IM2012
DATE: 06-08-00
50LD
TRIP A
OR
1
3 CYC
RTTD
IA
TA
AND
2
AND
1
AND
3
OR
2
DRTE
RELAY OR
MANUAL TRIP
Figure 2.12: Time-Delayed Retrip Logic (SEL-2BFR Relay)
Time-Delayed Breaker Retrip (SEL-2BFR-2 Relay)
Figure 2.13 shows one phase of the current supervised, time-delayed retrip logic. This logic
provides the ability to energize a redundant trip coil of the protected breaker after a fixed time
delay. The RTTD (Retrip Time Delay) timer provides the retrip time delay. The RTSD (Retrip
Seal-In Delay) timer provides a retrip seal-in delay to prevent seal-in during noisy conditions in
the TRIP A input.
Enable the time-delayed retrip by setting DRTE (Delayed Retrip Enable) equal to Y. The RTSD
timer has a default setting of 0.25 to provide a quarter-cycle seal-in delay. To increase the seal-in
delay of the trip input, enter the desired delay in the RTSD setting (Note: This setting should be
less than the RTTD setting). Timers RTTD and RTSD will start timing when the A-phase trip
input is asserted and the A-phase current is above the 50LD relay element setting. When the
RTSD time expires, the TRIP A input will seal in. The RTTD timer will run as long as A-phase
current is above the 50LD setting and the TRIP A input is asserted or sealed in. Relay word bit
TA will be set when the RTTD timer expires and will remain asserted for three cycles after the
50LD element drops out. Use the TA bit in a programmable output mask to utilize the retrip
logic. See
Section 5: Applications
.
Set the DRTE equal to N to bypass the current-supervised, time-delayed retrip logic. The TA
Relay Word bit will immediately assert or deassert after the TRIP A input asserts or deasserts,
respectively.
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