P.4.2
SEL-411L Relay Protection Manual Date Code 20151029
Autoreclosing and Synchronism-Check
Autoreclosing
The synchronism-check function uses single-phase input voltages V
S1
, V
S2
(source voltages), and reference V
P
(polarizing voltage) to provide
synchronism-check for one or two circuit breakers. The relay determines
when V
S1
and V
S2
are within programmable voltage magnitudes and slip
frequency windows compared to V
P
. In addition, the synchronism-check
function can use settable circuit breaker closing times and the measured slip
frequencies to compensate the angle difference calculation between V
S1
and
V
P
(plus V
S2
and V
P
). The relay checks this angle difference calculation in a
programmable synchronism angle window.
Autoreclosing
Logical States
The autoreclose logic for either circuit breaker can be in one of five states (see
Figure 4.1):
➤ 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
following conditions:
➤ Power-up
➤ 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.
When the relay is turned on 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 automatic 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. Setting 79BRCT (block reclaim timer) prevents
timing of reclaim timers SPRCD and 3PRCD.
To Next Page
Loading...
