Date Code 20001006
Close and Reclose Logic
6-11
SEL-351 Instruction Manual
SEL-351(1) Relay
Before allowing circuit breaker 52/1 to be reclosed after an open interval time-out, the SEL-351(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
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
SEL-351(2) Relay
The SEL-351(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
where:
25A1
= selected Bus 2 phase voltage (VA, VB, or VC) is in synchronism with monitored
single-phase transmission line voltage (channel VS) and both are hot
Other Setting Considerations for SEL-351(1) and SEL-351(2) Relays
Refer to
Skip Shot and Stall Open Interval Timing Settings (79SKP and 79STL, respectively)
in
the following
Reclosing Relay
subsection.
SEL
OGIC
Control Equation setting 79STL stalls open interval timing if it asserts to logical 1. If
setting 79STL is deasserted to logical 0, open interval timing can continue.
The SEL-351(1) Relay has no intentional open interval timing stall condition (circuit breaker 52/1
closes first after a transmission line fault):
79STL
= 0
(numeral 0)
The SEL-351(2) Relay starts open interval timing after circuit breaker 52/1 at the remote end has
reenergized the line. The SEL-351(2) Relay has to see Bus 2 hot, transmission line hot, and in
synchronism across open circuit breaker 52/2 for open interval timing to begin. Thus, SEL-351(2)
Relay open interval timing is stalled when the transmission line voltage and Bus 2 voltage are not
in synchronism across open circuit breaker 52/2:
79STL
= !25A1
[=NOT(25A1)]
Summary of Contents for SEL-351
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