Sel SEL-351S - Page 64

2.28
SEL-351S Relay Instruction Manual Date Code 20080103
Installation
SEL-351S AC/DC Connection Diagrams for Various Applications
Voltage Channel VS 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) and Broken-Delta
VS Connection (Global Setting VSCONN = 3V0) on page 2.20.
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 2.20 SEL-351S 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-2032/2030/2020
ALARM
(+)
(—)
Breaker Status
IN101
(+)
(—)
Comm.-Assisted
Trip Scheme
IN102
TRANSFORMER BANK