Sel 751A - Close Logic Can Still Operate When the Reclosing Relay Is Defeated; Defeat the Reclosing Relay

4.62
SEL-751A Relay Instruction Manual Date Code 20100129
Protection and Logic Functions
Reclose Logic
If the relay happened to be in the Reclose Cycle State and was timing on an
open interval before the settings change, the relay would be in the Reclose
Cycle State after the settings change, but the relay would immediately go to
the Lockout State. This is because the breaker is open, and the relay is at last
shot after the settings change, and thus no more automatic reclosures are
available.
If the circuit breaker remains closed through the settings change, the reset
timer times out on reset time setting 79RSLD after the settings change and
goes to the Reset State (if it is not already in the Reset State), and the shot
counter returns to shot = 0. If the relay happens to trip during this reset timing,
the relay will immediately go to the Lockout State, because shot = last shot.
Defeat the Reclosing
Relay
If any one of the following reclosing relay settings are made:
➤ Reclose enable setting E79 = OFF.
➤ Open Interval 1 time setting 79OI1 = 0.00.
then the reclosing relay is defeated, and no automatic reclosing can occur.
If the reclosing relay is defeated, the following also occur:
➤ All three reclosing relay state Relay Word bits (79RS, 79CY,
and 79LO) are forced to logical 0 (see Table 4.26).
➤ All shot counter Relay Word bits (SH0, SH1, SH2, SH3, and
SH4) are forced to logical 0 (the shot counter is explained later
in this section).
➤ The front-panel LEDs RECL RESET and RECL LOCKOUT are both
extinguished.
Close Logic Can Still Operate When the Reclosing Relay Is Defeated
If the reclosing relay is defeated, the close logic (see Figure 4.30) can still
operate if SEL
OGIC control equation circuit breaker status setting 52A is set to
something other than numeral 0 or NA. Making the setting 52A := 0 or NA
defeats the close logic and also defeats the reclosing relay.
For example, if 52A := IN101, a 52a circuit breaker auxiliary contact is
connected to input IN101. If the reclosing relay does not exist, the close logic
still operates, allowing closing to take place via SEL
OGIC control equation
setting CL (close conditions, other than automatic reclosing). See Trip/Close
Logic for more discussion on SEL
OGIC control equation settings 52A and CL.