6.11
Date Code 20080213 Instruction Manual SEL-351A Relay
Close and Reclose Logic
Reclose Supervision Logic
Referring again to the above-referenced subsection, note item 3 under
Synchronism Check Element Outputs, Voltages V
P
and V
S
are “Slipping” and
Setting TCLOSD
≠
0.00 on page 3.46. 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 6.6 and Table 6.3), the reclosing
relay is then driven to the Lockout State.
Courtesy of NationalSwitchgear.com
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