6.12
SEL-351S Relay Instruction Manual Date Code 20080103
Close and Reclose Logic
Reclose Supervision Logic
SEL-351S(2)
The SEL-351S(2) 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:
Other Setting Considerations for SEL-351S(1) and SEL-351S(2)
Refer to Skip Shot and Stall Open-Interval Timing Settings (79SKP and
79STL, Respectively) on page 6.24.
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-351S(1) 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-351S(2) starts open-interval timing after circuit breaker 52/1 at the
remote end has reenergized the line. The SEL-351S(2) 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-351S(2) 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)]
A transient synchronism check condition across open circuit breaker 52/2
could possibly occur if circuit breaker 52/1 recloses into a fault on one
phase of the transmission line. The other two unfaulted phases would be
briefly energized until circuit breaker 52/1 is tripped again. If Channel VS
of the SEL-351S(2) is connected to one of these briefly energized phases,
synchronism check element 25A1 could momentarily assert to logical 1.
So that this possible momentary assertion of synchronism check element
25A1 does not cause any inadvertent reclose of circuit breaker 52/2, make
sure the open-interval timers in the SEL-351S(2) are set with some
appreciable time greater than the momentary energization time of the
faulted transmission line. Or, run the synchronism check element 25A1
through a programmable timer before using it in the preceding 79CLS
and 79STL settings for the SEL-351S(2) (see Figure 7.25 and
Figure 7.26). Note the built-in 3-cycle qualification of the synchronism
check voltages shown in Figure 3.26.
Additional Settings
Example 2
Refer to subsection Synchronism Check Elements on page 3.36. Also refer to
Figure 6.6 and Figure 6.7.
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
Artisan Technology Group - Quality Instrumentation ... Guaranteed | (888) 88-SOURCE | www.artisantg.com
To Next Page
Loading...
