2.32
SEL-351A Relay
Instruction Manual
Date Code 20080213
Installation
SEL-351A AC/DC Connection Diagrams for Various Applications
The voltage inputs can accept open-delta PT (three-wire) connection (as shown) when Global setting PTCONN = DELTA.
VB
(terminal
Z10
) must be externally tied to
N
(terminal
Z12
), as shown. (For Connectorized relays, this connection must be
made at the remote end of the wiring harness).
Voltage channel
VS-NS
(SEL-351A only) is shown connected for use in voltage and synchronism check elements and
voltage metering. See
Synchronism Check VS Connection (Global setting VSCONN = VS) on page 2.15
. The synchronism-
check voltage is shown coming from C-phase, via a line-to-ground connection. To account for the phase difference
between V
C
and V
AB
, use group setting SYNCP = 270 (degrees lagging V
AB
, with ABC rotation). See
Elements (Not in SEL-351A-1) on page 3.36
.
Current Channel
IN
does not need to be connected. Channel
IN
provides current I
N
for the neutral-ground overcurrent
elements. Separate from Channel
IN
, the residual-ground overcurrent elements operate from the internally derived
residual current I
G
(I
G
= 3I
0
= I
A
+ I
B
+ I
C
). But, in this residual connection example, the neutral-ground and residual-
ground overcurrent elements operate the same because I
N
= I
G
.
Figure 2.24
SEL-351A Provides Overcurrent Protection and Reclosing for a Utility Distribution Feeder (Open-
Delta Connected PTs and Line-to-Ground Synchronism-Check Connection)
TC
Trip
Coil
52A
(+)
(—) Trip
Circuit
IA
C
B
A
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
VS
NS
FEEDER
52
(+)
OUT104
(+)
52A
to Annunciator, RTU,
or SEL-2032/SEL-2030/SEL-2020
to Bus Relay
(Fast Bus Trip Scheme)
ALARM
(+)
(—)
Breaker Status
IN101
N
VC
VB
VA
Open-Delta
Summary of Contents for SEL-351A
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