R.2.27
Date Code 20111215 Reference Manual SEL-421 Relay
Auto-Reclosing and Synchronism Check
Auto-Reclose Logic Diagrams
External Recloser
If reclosing is performed by an external relay, assert SELOGIC control
equations E3PT, E3PT1, and E3PT2 via control inputs (for example):
E3PT := IN104 Three-Pole Trip Enable (SELOGIC Equation)
E3PT1 := IN105 Breaker 1 Three-Pole Trip (SELOGIC Equation)
E3PT2 := IN106 Breaker 2 Three-Pole Trip (SELOGIC Equation)
Connect the external recloser single-pole trip output signal to IN104, the
Circuit Breaker BK1 trip type signal to IN105, and the Circuit Breaker BK2
trip type signal to IN106. Other external recloser signals are required; consult
the external recloser documentation for interconnection with the SEL-421.
In installations where the external reclosing relay does not provide three-phase
trip control signals, the TOP (Trip during Open-Pole) Relay Word bit can be
used in the E3PT setting. See Figure 1.71 on page R.1.115. This Relay Word
bit will assert just after a single- or two-pole trip, and remain asserted until the
TOPD timer expires. If a new trip occurs during this time, the E3PT := TOP
setting would then cause a three-pole trip.
Auto-Reclose Logic Diagrams
Figure 2.5 Circuit Breaker Pole-Open Logic Diagram
52AA1
52AB1
52AC1
SPOBK1
3POBK1
52AA1D
52AB1D
52AC1D
Timers in cycles
2POBK1
Note: Similar logic for Breaker 2
0
1.0
0
1.0
0
1.0
Relay
Word Bits
Relay
Word Bits
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