2.23
Date Code 20080213 Instruction Manual SEL-351A Relay
Installation
SEL-351A AC/DC Connection Diagrams for Various Applications
Voltage Channel VS (in SEL-351A) does not need to be connected. Here, it 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 and Broken-Delta VS Connection (Global setting VSCONN = 3V0) on page 2.15.
In this example, current Channel IN provides current polarization for a directional element used to control 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
).
Figure 2.15 SEL-351A Provides Directional Overcurrent Protection and Reclosing for a Transmission Line
(Current Polarization Source Connected to Channel IN) (Wye-Connected PTs)
TC
Trip
Coil
52A
(+)
(—)
Trip
Circuit
IA
C
B
A
NVCVB
SEL-351 RELAY
VA
OUT101
Forward Tripping Direction
CC
Close
Coil
52B
(+)
(—)
Close
Circuit
IB
OUT102
86
Lock
Out
86B
(+)
(—)
Breaker
Failure Trip
Circuit
IC
OUT103
IN
VS
NS
LINE
52
TX
(+)
(—)
Comm.-
Assisted
Trip
Scheme
OUT104
(+)
RX
52A
to Annunciator, RTU,
or SEL-2032/SEL-2030/SEL-2020
ALARM
(+)
(—)
Breaker Status
IN101
(+)
(—)
Comm.-Assisted Trip
Scheme
IN102
TRANSFORMER BANK
Courtesy of NationalSwitchgear.com
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