
GENERAL DESCRIPTION
Page 13
CONTROLLER
COMPARTMENT
A .
Isolation Switch (Fig. 9)
P o w e r i s s w i t c h e d o n a n d o f f t o e a c h
individual controller compartment by a
mounted,
externally-operated,
three-pole
isolation switch. When the switch is in the
open position, incoming power is isolated from
the compartment interior by an automatic
shutter. Also, the load terminals of the switch
a r e a u t o m a t i c a l l y g r o u n d e d i n t h e o p e n
position for additional safety.
The isolation switch is designed to accept a
direct connection from the line stabs of the
withdrawable
contactor
carriage.
This
connection is automatically made when the
contactor carriage is installed in the medium
voltage compartment.
When the switch is
closed by operating the external handle,
incoming power is applied to the line side of
the power fuses. In this position, the motor or
other load may be switched on and off by
operating
the
vacuum
contactor.
T h e
isolation
s w i t c h
is
mechanically
interlocked with the vacuum contactor and the
compartment
door.
Details of the interlocking
are discussed in section H.
The position of the isolation switch blades can
be observed through a window in the medium
voltage compartment door. Thus, it is possible
to have visual evidence that the power source
is isolated before entering the medium voltage
compartment.
The switch is also provided
with lock-out provisions (Fig. IO).
T h e i s o l a t i o n s w i t c h h a s a m a x i m u m
interrupting capacity of 0.4 amperes.
D o
n o t
c o n n e c t
additional load to the
isolation switch.
Fig.
9
Isolation Switch
Fig. 10 Isolation Switch Lockout
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