Schweitzer Engineering Laboratories SEL-351A - Figure 2.14 SEL-351 A Provides Directional Overcurrent Protection and Reclosing for a Transmission Line (Wye-Connected Pts)

2.22
SEL-351A Relay Instruction Manual Date Code 20080213
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.
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 2.14 SEL-351A 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/SEL-2030/SEL-2020
ALARM
(+)
(—)
Breaker Status
IN101
RX
(+)
(—)
Comm.-Assisted Trip
Scheme
IN102
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