Schweitzer Engineering Laboratories SEL-351-5, Instruction Manual

Page: 71 / 706

2.31
Date Code 20070117
Instruction Manual SEL-351-5, -6, -7 Relay
Installation
AC/DC Connection Diagrams for Various Applications
The voltage inputs can accept open-delta PT (three-wire) connection (as shown) when global setting PTCONN = DELTA.
Voltage terminal VB (Z10) must be tied to voltage terminal N (Z12) , as shown. (For Connectorized relays, this connection
must be made at the remote end of the wiring harness).
Voltage Channel VS 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 2.14 . The synchronism check voltage is shown
coming from C-phase, via a line-to-ground connection. To account for the phase difference between VC and VAB, use
group setting SYNCP = 270 (degrees lagging V
AB
, with ABC rotation). See Synchronism Check Elements on page 3.33 .
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 2.22 Utility Distribution Feeder Overcurrent Protection and Reclosing (Delta Connected PTs and Line-to-
Ground Synchronism Check Connection)
TC
Trip
Coil 52A
(+)
(—) Trip
Circuit
IA
C
B
A
SEL-351 RELAY
OUT101
Forw
ar
d T
ripping Dir
ection
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
N VC VB VA