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2.26
SEL-351A Relay
Instruction Manual
Date Code 20080213
Installation
SEL-351A AC/DC Connection Diagrams for Various Applications
A core-balance current transformer is often referred to as a zero-sequence, ground fault, or window current
transformer.
Pass neutral (N) through the core-balance CT only if the neutral is brought out and it is grounded only at the source.
Although automatic reclosing is probably not needed in this example, output contact
OUT102
can close the circuit breaker
via initiation from various means (serial port communications, optoisolated input assertion, etc.), with desired
supervision.
For sensitive earth fault (SEF) applications, the SEL-351A should be ordered with channel
IN
rated at 0.2 A or 0.05 A
nominal. See
. See neutral-ground overcurrent element pickup specifications in
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
. See also the note following
Figure 2.18
SEL-351A Provides Overcurrent Protection for an Industrial Distribution Feeder (Core-Balance
Current Transformer Connected to Channel IN)
TC
Trip
Coil
52A
(+)
(—) Trip
Circuit
IA
SEL-351 RELAY
OUT101
Forw
ar
d T
ripping Dir
ection
CC
Close
Coil
52B
(+)
(—) Close
Circuit
IB
OUT102
86
Lock
Out
86B
(+)
(—) Breaker
Failure Trip
Circuit
IC
OUT103
IN
52
(+)
52A
to Annunciator, RTU,
or SEL-2032/SEL-2030/SEL-2020
ALARM
(+)
(—)
Breaker Status
IN101
FEEDER
A
N
B
C
Summary of Contents for SEL-351A
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