Schweitzer Engineering Laboratories SEL-751 - Figure 4.84 Reclosing Relay States and General Operation

4.138
SEL-751 Relay Instruction Manual Date Code 20170927
Protection and Logic Functions
Group Settings (SET Command)
The reclose enable setting, E79, has setting choices N, 1, 2, 3, 4, C1, C2, C3,
and C4. Setting E79 := N defeats the reclosing relay. Setting choices 1–4 and
C1–C4 are the number of automatic reclosures (see Open Interval Timers on
page 4.141) you want. With setting choices 1–4, the reclosing relay goes to
the lockout state on reclose supervision failure (refer to Reclose Supervision
Logic on page 4.131).
With setting choices C1–C4, however, the reclosing relay does not go to the
lockout state on reclose supervision failure. Instead, the reclosing relay incre-
ments the shot counter and starts timing on the next open interval. This opera-
tion emulates a rotating drum timer style reclosing relay—going on to the next
open interval time and reclose opportunity when supervising conditions for
the present reclose opportunity are not true.
Reclosing Relay States and General Operation
Figure 4.84 explains in general the different states of the reclosing relay and
its operation.
Figure 4.84 Reclosing Relay States and General Operation
All Automatic Reclosing
Attempts Unsuccessful
Unsuccessful
Reclose Initiation
Other Lockout Conditions
Power Up
Reset
Timer
Times
Out
Reset
Timer
Times
Out
Other
Lockout
Conditions
Unsuccessful
Reclose
Initiation
Successful
Reclose
Initiation
Successful
Reclose Initiation
Maintained
Lockout Condition
Lockout State
All automatic reclosing attempts are
unsuccessful, reclose initiation is unsuccessful,
other lockout conditions occur, or the SEL-751
powers up. The relay returns to the reset state
after the circuit breaker is closed, the reset
timer times out, and there are no maintained
lockout conditions.
Relay Word bit 79LO = logical 1
Front-panel pushbutton LED 1B
labeled RECL LOCKOUT illuminated
Reclose Cycle State
The SEL-751 automatically recloses the
circuit breaker after each successful
reclose initiation and corresponding set
open interval time.
Relay Word bit 79CY = logical 1
Reset State
The circuit breaker has been closed
for a qualifying reset time. The SEL-751 is
ready to go through an automatic
reclosing sequence in the reclose cycle
state if the circuit breaker trips open
and reclose initiation is successful.
Relay Word bit 79RS = logical 1
Front-panel pushbutton LED 1A
labeled RECL RESET illuminated