Schweitzer Engineering Laboratories SEL-421-4 - Page 481

6.145
Date Code 20171021 Instruction Manual SEL-421 Relay
Protection Applications Examples
Autoreclose and Synchronism-Check Example
Drive the autoreclose logic to lockout if the SEL-421 detects a loss-of-potential
condition.
79DTL := LOP. Recloser Drive to Lockout (SELOGIC Equation)
You can block reclaim timing. However, it is not necessary for this application example.
79BRCT := NA. Block Reclaim Timer (SELOGIC Equation)
When leaving the lockout condition, the recloser goes to the Ready or Reset state
after the 3PMRCD (Manual Close Reclaim Time Delay) timer has expired.
3PMRCD := 900. Manual Close Reclaim Time Delay (1–99999 cycles)
If Circuit Breaker 1 reclose supervision conditions (settings SP1CLS and 3P1-
CLS) fail to occur within 300 cycles after the three-pole open interval time delay
expires, the autoreclose logic goes to lockout.
BK1CLSD := 300. BK1 Reclose Supervision Delay (OFF, 1–99999 cycles)
If Circuit Breaker 2 reclose supervision conditions (settings SP2CLS and 3P2-
CLS) fail to occur within 300 cycles after the three-pole open interval time delay
expires, the autoreclose logic goes to lockout.
BK2CLSD := 300. BK2 Reclose Supervision Delay (OFF, 1–99999 cycles)
Single-Pole Autoreclose Logic
Initiate a single-pole autoreclose cycle whenever the SEL-421 single-pole trips.
Autoreclose is blocked if a manual, time-delayed, bus, or circuit breaker failure
trip occurs. None of these events generate a single-pole trip (see Autoreclose
Conditions on page 6.143).
Set the single-pole open interval time equal to one second.
SPOID := 60. Single-Pole Open Interval Delay (1–99999 cycles)
Set the reclaim time following a single-pole autoreclose cycle equal to 900 cycles.
SPRCD := 900. Single-Pole Reclaim Time Delay (1–99999 cycles)
Initiate a single-pole autoreclose cycle whenever the SEL-421 single-pole trips.
SPRI := SPT AND (Z1G OR COMPRM). Single-Pole Reclose Initiation
(SEL
OGIC Equation)
No supervision is required before Circuit Breaker 1 attempts a single-pole
reclose. The SEL-421 autoreclose logic only applies synchronism supervision
during a single-pole autoreclose cycle in this application example (setting cannot
be set to NA or logical 0).
SP1CLS := 1. Single-Pole BK1 Reclose Supervision (SELOGIC Equation)
No supervision is required before Circuit Breaker 2 attempts a single-pole reclose
when this circuit breaker is the leader. The SEL-421 autoreclose logic only
applies synchronism supervision during a single-pole autoreclose cycle in this
application example (setting cannot be set to NA or logical 0).
SP2CLS := NOT LEADBK1. Single-Pole BK2 Reclose Supervision
(SEL
OGIC Equation)