U.2.49
Date Code 20020501
User’s Guide
SEL-421/SEL-421-1 Relay
Installation
AC/DC Connection Diagrams
Figure 2.32
Typical External AC/DC Connections—Dual Circuit Breaker.
Circuit
Breaker 1
Circuit
Breaker 2
ICW
IBW
IAW
IAX
IBX
ICX
BK1 CTs
BK2 CTs
LINE PTs
A
BUS 1
SEL-421 Relay
B
C
A
BUS 2
B
C
A
B
C
LINE
Forward Direction
Synch-Check
Circuit Breaker 1
VAZ
PT Send
DTT Send
OUT104
(+)
(—) Permissive
Trip Send
(to Comm.
Transmitter)
(+)
(—) Direct Transfer
Trip Send
OUT105
Alarm to
Annunciator, RTU,
or SEL-2020/2030
(+)
OUT108
Trip Coil 52A1
OUT101
(+)
(—) Breaker 1
Trip Circuit
TC
Close Coil 52B1
OUT102
(+)
(—) Breaker 1
Close Circuit
CC
Lock Out 86B1
OUT103
(+)
(—) Bus 1
Breaker Failure
Trip Circuit
86
Trip Coil 52A2
OUT201
(+)
(—) Breaker 2
Trip Circuit
TC
Close Coil 52B2
OUT202
(+)
(—) Breaker 2
Close Circuit
CC
Lock Out 86B2
OUT203
(+)
(—) Bus2
Breaker Failure
Trip Circuit
86
Synch-Check
Circuit Breaker 2
VBZ
VCY
VBY
VAY
(+)
(—)
Power
Power
(+)
(—)
Vdc1
Monitor Vdc1
(Station Battery)
(+)
(—)
Vdc2
Monitor Vdc2
(Trip Circuits,
Comms)
IN101
(+)
(—)
52A1
Breaker Status 1
(—)
IN102
Bus 1
Breaker Failure
Lock Out
BF LO
(+)
IN103
(+)
(—)
PT RX
Permissive Trip
Receive
(—)
IN104
Direct Transfer
Trip Receive
DTT RX
(+)
IN201
(+)
(—)
52A2
Breaker Status 2
(—)
IN202
Bus 2
Breaker Failure
Lock Out
BF LO
(+)
52-1
52-2
Summary of Contents for SEL-421
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