Sel 411L - Page 460

P.4.6
SEL-411L Relay Protection Manual Date Code 20151029
Autoreclosing and Synchronism-Check
One-Circuit-Breaker Autoreclosing
➤ If a multiphase fault occurs during the SPRCD reclaim time,
then the recloser asserts Relay Word bit 3PARC if all three-pole
reclose conditions are satisfied (E3PR1 is logical 1, for
example) and proceeds to the autoreclose three-pole cycle state
79CY3.
➤ If a multiphase fault occurs during the SPRCD reclaim time,
and the three-pole reclose conditions are not satisfied (E3PR1
is logical 0, for example), the recloser exits the 79CY1 cycle
state and goes to the lockout state BK1LO.
Lockout State from 79CY1
The recloser goes to lockout (BK1LO) when the number of trips exceeds the
maximum number of shots (NSPSHOT), supervision condition SP1CLS fails
to assert in BK1CLSD time, Relay Word bit 3POLINE asserts (for a circuit
breaker manual opening), the circuit breaker fails to close within BKCFD
time, or any time Relay Word bit 79DTL asserts.
Three-Pole Mode
Figure 4.11 shows the one circuit breaker autoreclose cycle 79CY3. The cycle
starts when Relay Word bit 3PARC asserts. The recloser checks SEL
OGIC
control equation 79SKP at this point to determine whether to increment the
shot counter. The recloser waits indefinitely for the circuit breaker to open, as
indicated by Relay Word bit 3POLINE. The recloser begins timing 3POID1
(Three-Pole Open Interval 1 Delay) when the circuit breaker opens. After the
open interval time 3POID1 expires, the relay asserts Relay Word bit BK1CL
to reclose the circuit breaker if supervisory condition 3P1CLS (Three-Pole
BK1 Reclose Supervision) is satisfied within the duration of timer BK1CLSD
(BK1 Reclose Supervision Delay).
At the reclose command, the recloser starts timer BKCFD (Breaker Close
Failure Delay). If the circuit breaker fails to close, the recloser goes to lockout
(BK1LO) after timer BKCFD expires.
3PRCD Reclaim Timing
If the circuit breaker closes, the recloser starts timer 3PRCD (Three-Pole
Reclaim Time Delay). The recloser determines subsequent state transitions
during reclaim timing according to the status of Relay Word bit 3PLSHT
(Three-Pole Reclose Last Shot).
3PLSHT Asserted (Last Shot). The recloser exits the 79CY3 state via
two methods while 3PLSHT is asserted:
➤ If no further trip conditions occur, the recloser goes to the reset
state BK1RS after reclaim timer 3PRCD expires.
➤ If a fault occurs during the 3PRCD reclaim time, then the
recloser exits the 79CY3 cycle state and goes to the lockout
state BK1LO.