14
Types SDV-R and SDV-R-AR distribution circuit breakers |
Instruction manual
Ground connections
Grounding pads on diagonally opposite
corners of the enclosure are provided for
connecting the cabinet to ground. A ground
pad is provided on the bottom surface of the
enclosure for connecting the grounding
switch terminals to ground. This ground pad
must be rotated from the “shipping” position
to the “installed” position as shown in Figure
5: Ground switch connection pad installation
on page 15 by reusing the M12 hardware
supplied and tightening the bolts to 52 ft-lb
(70 Nm).
The grounding conductors should be at least
4/0 AWG conductor for all ground
connections. A good low-resistance ground is
essential for adequate protection and for
proper functioning of electronic components
such as protective relays. Connections to
ground pads must be made in such a manner
that a reliable ground connection is obtained.
Consult latest National Electrical Code® or
National Electric Safety Code® for ground
connection standards.
Primary lead connections
The primary leads must be routed to the
bushing terminals to maintain adequate
dielectric clearance between different phase
conductors and to ground. Conductors must
be supported so that the circuit breaker
bushings are not subjected to excessive
strains, both during normal service and in the
event of a short-circuit condition. The leads
should be sized to have a capacity at least
equal to the maximum operating current of
the circuit and within the rating of the type
SDV-R distribution circuit breaker.
Connections are to be made to the bolted
aerial lug terminals of the bushings (normally
customer supplied unless otherwise specified)
and must be securely tightened to a clean,
bright surface to assure good contact.
Secondary control wiring
All secondary control wiring installed by the
factory is neatly routed and secured in place.
Complete all field connections in a similar
manner. Check that the protective relay panel
(if so equipped) clears any additional wiring
installed.
A conduit panel opening is provided in the
bottom of the relay and control compartment
for the connection of control circuits. The
control wires should be run separately from
high-voltage wiring to prevent inductive
coupling between them and should be sized
for full operating current to avoid a drop in
voltage below that specified on the
nameplate. All conduits should be sealed off
at their entrance to the relay and control
compartment.
Terminal blocks are provided inside the relay
and control compartment for the connections
necessary for the control wiring and
protective relay panel (if so equipped).
Terminal blocks for current transformer wiring
are located in the relay and control
compartment and wires can easily be routed
from the conduit panel opening in the relay
and control compartment to the current
transformer circuit terminal blocks in the relay
and control compartment. Consult the
connection diagrams for the location of
connection terminal points for each circuit.
Connection diagrams are provided with each
type SDV-R distribution circuit breaker and
will be found in the pocket inside the relay
and control compartment door.
Hazardous voltages and high speed moving parts.
Will cause death, serious injury or property damage.
Do not work on energized equipment and SDV-R integral ground switch
is not meant to be a personnel safety ground. Always de-energize and
ground high-voltage conductors before working on or near them. The
user must make all ground connections before making high-voltage
connections, adjust the circuit breaker height to ensure compliance with
safety codes for electrical clearance, and assure that the arc-exhaust
vents are at least 79” (2.0 m) above finished grade.
Important:
An induced voltage
can be present on the load side
of an open vacuum interrupter.
To minimize any potential
hazards to operating
personnel, the ground
connections must be
connected before the high
voltage connections. Separate
connections for the grounding
switch and enclosure ground
must be used.
Electrical connections
