Sel SEL-351S - Page 63

2.27
Date Code 20080103 Instruction Manual SEL-351S Relay
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.
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 2.19 SEL-351S Provides Directional Overcurrent Protection and Reclosing for a Transmission Line
(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
TX
(—)
Comm.-
Assisted
Trip
Scheme
IC
OUT103
IN
VS
NS
LINE
52
(+)
OUT104
(+)
52A
to Annunciator, RTU,
or SEL-2032/2030/2020
ALARM
(+)
(—)
Breaker Status
IN101
RX
(+)
(—)
Comm.-Assisted
Trip Scheme
IN102