2.28
SEL-751A Relay
Instruction Manual
Date Code 20100129
Installation
AC/DC Control Connection Diagrams
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.
For sensitive earth fault (SEF) applications, the SEL-751A should be ordered with Channel
IN
rated at 2.5 mA nominal.
See current input specifications in the subsection
. See neutral ground overcurrent
element pickup specifications in
Section 4: Protection and Logic Functions
.
Figure 2.24
SEL-751A Provides Overcurrent Protection for an Industrial Distribution Feeder
(Core-Balance Current Transformer Connected to Channel IN)
TC
Trip
Coil
52A
(+)
(—) Trip
Circuit
IA
SEL-751A RELAY
OUT103
CC
Close
Coil
52B
(+)
(—) Close
Circuit
IB
OUT102
86
Lock
Out
86B
(+)
(—) Breaker
Failure
Trip
Circuit
IC
OUTxxx
IN
52
(+)
52A
to Annunciator, RTU,
or SEL-2032/2030/2020
ALARM
OUT101
(+)
(—)
Breaker Status
INxxx
FEEDER
A
N
B
C
A
B
C
N
BUS
Содержание 751A
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