Schweitzer Engineering Laboratories SEL-421-4 - Page 978

6.2
SEL-400 Series Relays Instruction Manual Date Code 20171006
Autoreclosing
Autoreclosing States
Autoreclosing States
The autoreclose logic for either circuit breaker can be in one of the following five
states (see Figure 6.1):
➤ Start (common to both circuit breakers) (79STRT)
➤ Reset per circuit breaker (BK1RS, BK2RS)
➤ Single-pole autoreclose cycle (common to both circuit breakers) (79CY1)
➤ Three-pole autoreclose cycle (common to both circuit breakers) (79CY3)
➤ Lockout, per circuit breaker (BK1LO, BK2LO)
Start (79STRT)
The autoreclose logic is in the Start state for both circuit breakers during the fol-
lowing conditions:
➤ Startup
➤ Restart
➤ Any relay settings change
The relay stores the previous reclosing state for Relay Word bits 79CY1, 79CY3,
BK1LO, BK2LO, BK1RS, and BK2RS when a restart or any relay settings
change occurs.
At startup, the recloser logic goes from the start state to the lockout state. For a
restart or a settings change, the recloser logic enters the start state, then goes to
lockout if the circuit breakers were open before the restart or settings change. If
the circuit breakers were previously closed, then the recloser logic proceeds
through the 3PMRCD (Manual Close Reclaim Time Delay) time and then goes to
the ready state.
Reset (BK1RS, BK2RS)
The autoreclose logic is in the reset or ready state for either circuit breaker when
the circuit breaker is ready to begin an autoreclose cycle. There are three reset
state timers. After a successful reclose cycle, the relay goes to the reset state after
reclaim times SPRCD (Single-Pole Reclaim Time Delay) for single-pole auto-
matic and 3PRCD (Three-Pole Reclaim Time Delay) for three-pole automatic
reclosing. If the recloser has been in a lockout condition, the Ready or Reset state
cannot occur until the 3PMRCD (Manual Close Reclaim Time Delay) timer has
expired. You can only block the reclaim time after a successful reclose cycle. Set-
ting 79BRCT (Block Reclaim Timer) prevents timing of reclaim timers SPRCD,
3PRCD, and 3PMRCD.
Single-Pole Autoreclose (79CY1)
This state does not apply to relays that only support three-pole reclosing. The
autoreclose logic is in a single-pole autoreclose cycle for either circuit breaker if
all of the following conditions are satisfied:
➤ Single-pole trip occurs
➤ Condition(s) to initiate a single-pole autoreclose cycle are satisfied
➤ Circuit breaker(s) is in-service and ready to begin a single-pole
autoreclose cycle (that is, reset)