6.13
Date Code 20080213 Instruction Manual SEL-351A Relay
Close and Reclose Logic
Reclosing Relay
Figure 6.5 Reclosing Relay States and General Operation
The reclosing relay is in one (and only one) of these states (listed in Table 6.1)
at any time. When in a given state, the corresponding Relay Word bit asserts to
logical 1, and the LED illuminates. Automatic reclosing only takes place
when the relay is in the Reclose Cycle State.
Lockout State
The reclosing relay goes to the Lockout State if any one of the following
occurs:
➤ The shot counter is equal to or greater than the last shot at time
of reclose initiation (e.g., all automatic reclosing attempts are
unsuccessful—see Figure 6.6).
Reset State
Reclose Cycle State
Lockout State
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
The circuit breaker has been closed
for a qualifying reset time. The SEL-351A
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 RS LED illuminated
The SEL-351A automatically recloses the
circuit breaker after each successful
reclose initiation and corresponding set
open interval time.
Relay Word bit 79CY = logical 1
Front-panel CY LED illuminated
All automatic reclosing attempts are
unsuccessful, reclose initiation is unsuccessful,
other lockout conditions occur, or the SEL-351A
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 LO LED illuminated
Table 6.1 Relay Word Bit and Front-Panel Correspondence to Reclosing Relay
States
Reclosing Relay State
Corresponding
Relay Word Bit
Corresponding
Front-Panel LED
Reset 79RS RS
Reclose Cycle 79CY CY
Lockout 79LO LO
Courtesy of NationalSwitchgear.com
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