6.9
Date Code 20080213 Instruction Manual SEL-351A Relay
Close and Reclose Logic
Reclose Supervision Logic
Factory Settings
Example
Refer to the top of Figure 6.2.
The factory setting for the SEL
OGIC control equation reclose supervision
setting is:
79CLS = 1 (numeral 1)
The factory setting for the Reclose Supervision Limit Timer setting is:
79CLSD = 0.00 cycles
Any time a reclosing relay open interval times out, it propagates immediately
through Figure 6.2 and then on to Figure 6.1, because SEL
OGIC control
equation setting 79CLS is always asserted to logical 1. Effectively, there is no
special reclose supervision.
Additional Settings
Example 1
Refer to the top of Figure 6.2 and Figure 6.4.
SEL-351A relays are installed at both ends of a transmission line in a high-
speed reclose scheme. After both circuit breakers open for a transmission line
fault, the SEL-351A(1) Relay recloses circuit breaker 52/1 first, followed by
the SEL-351A(2) Relay reclosing circuit breaker 52/2, after a synchronism
check across circuit breaker 52/2.
NOTE: Does not apply to the
SEL-351A-1.
Figure 6.4 SEL-351A Relays Installed at Both Ends of a Transmission Line
in a High-Speed Reclose Scheme
SEL-351A(1) Relay
Before allowing circuit breaker 52/1 to be reclosed after an open interval time-
out, the SEL-351A(1) Relay checks that Bus 1 voltage is hot and the
transmission line voltage is dead. This requires reclose supervision settings:
79CLSD = 0.00 cycles (only one check)
79CLS = 3P59 * 27S
SEL-351A(2) Relay
The SEL-351A(2) Relay checks that Bus 2 voltage is hot, the transmission
line voltage is hot, and in synchronism after the reclosing relay open interval
times out, before allowing circuit breaker 52/2 to be reclosed. This requires
reclose supervision settings:
79CLSD = 0.00 cycles (only one check)
79CLS = 25A1
SEL-351A (1)
Bus 1 Bus 2
52
1
52
2
IA, IB, IC
VA, VB, VC
VS
SEL-351A (2)
IA, IB, IC
VA, VB, VC
VS
3-Phase 3-Phase
1-Phase
where:
3P59 = all three Bus 1 phase voltages (VA, VB, and VC) are hot
27S = monitored single-phase transmission line voltage (channel
VS) is dead
Courtesy of NationalSwitchgear.com
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