6.13
Date Code 20080103 Instruction Manual SEL-351S Relay
Close and Reclose Logic
Reclose Supervision Logic
If the synchronizing voltages across open circuit breaker 52/2 are “slipping”
with respect to one another, the Reclose Supervision Limit Timer setting
79CLSD should be set greater than zero so there is time for the slipping
voltages to come into synchronism. For example:
79CLSD = 60.00 cycles
79CLS = 25A1
The status of synchronism check element 25A1 is checked continuously
during the 60-cycle window. If the slipping voltages come into synchronism
while timer 79CLSD is timing, synchronism check element 25A1 asserts to
logical 1 and reclosing proceeds.
In the above referenced subsection Synchronism Check Elements on
page 3.36, note item 3 under Synchronism Check Element Outputs on
page 3.46, Voltages V
P
and V
S
are “Slipping.” Item 3 describes a last attempt
for a synchronism check reclose before timer 79CLSD times out (or setting
79CLSD = 0.00 and only one check is made).
➤ If E79 = 3 (which allows three automatic reclose attempts) and
the slipping voltages fail to come into synchronism while timer
79CLSD is timing (resulting in a reclose supervision failure,
causing RCSF to assert for one processing interval), then the
reclosing relay goes to the Lockout State.
➤ If E79 = C3 (which allows three automatic reclose attempts)
and the slipping voltages fail to come into synchronism while
timer 79CLSD is timing (resulting in a reclose supervision
failure, causing RCSF to assert for one processing interval),
then the reclosing relay increments the shot counter and starts
timing on the next open interval. This operation emulates a
rotating drum timer style reclosing relay-going onto the next
open interval time and reclose opportunity if supervising
conditions for the present reclose opportunity are not true. If
the reclosing relay increments to the last shot value (no more
open intervals left; see Figure 6.9 and Table 6.3), the reclosing
relay is then driven to the Lockout State.
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