Schweitzer Engineering Laboratories SEL-351A - SEL-351 A AC;DC Connection Diagrams for Various Applications; Figure 2.12 SEL-351 A Provides Overcurrent Protection and Reclosing for a Utility Distribution Feeder (Includes Fast Bus Trip Scheme) (Wye-Connected Pts)

2.20
SEL-351A Relay Instruction Manual Date Code 20080213
Installation
SEL-351A AC/DC Connection Diagrams for Various Applications
SEL-351A AC/DC Connection Diagrams for Various
Applications
The voltage inputs do not need to be connected. Voltage is needed for voltage elements, synchronism check elements,
frequency elements, voltage-polarized directional elements, fault location, metering (i.e., voltage, MW, MVAR), and
frequency tracking. Voltage Channel VS (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 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 2.12 SEL-351A Provides Overcurrent Protection and Reclosing for a Utility Distribution Feeder (Includes
Fast Bus Trip Scheme) (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
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
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