Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 249 / 706

6.11
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Close and Reclose Logic
Reclose Supervision Logic
In the above referenced subsection Synchronism Check Elements , note item 3
under Synchronism Check Element Outputs on page 3.43 , 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 6.6 and Table 6.3 ), the reclosing
relay is then driven to the Lockout State.