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01.4IB.46300
Equipment Description
Starters are available with bolt-in or clip-in
main fuses. Contactors may have bolted
connections or stab-in connections to the
starter cell.
The flow of current through a starter with
bolted fuses and a stab-in contactor can be
described as follows:
The line finger assembly mounted at the
back of the enclosure serves to connect
the isolation switch moving stabs to the
controller line terminals when the switch is
closed. Power flows from the switch moving
stabs through a flexible shunt to the upper
fuse mountings. The fuses are connected to
the lower fuse mountings that contain the
line-side stab connections to the line finger
assemblies for the main contactor. With
the main contactor energized, power flows
through the contactor’s vacuum interrupters to
the contactor load fingers, which are engaged
on to the contactor load-side stabs. Medium
voltage cables connect the load-side stabs to
the motor load connections. The contactor is
held in place by a set of rails mounted in the
lower part of the cell. Current transformers
are typically mounted immediately behind
the main contactor, under the load-side stabs.
The motor load connections are mounted to
the left of the main fuses in the rear of the
compartment, facing forward.
Figure 2
Two-High Vertical Section Rear View
(400A)
To open the high voltage compartment
door, the power must be disconnected by
a sequence of manual operations which
require opening the medium voltage vacuum
contactor and deenergizing the load, operating
the isolating device, and unlatching the door.
The low voltage compartment door may be
entered without disconnecting the power.
The low voltage components are mounted
in the low voltage control compartment
located on the front of the controller
medium voltage door. The low voltage
compartment is fabricated from steel sheets
to provide isolation from the medium voltage
components mounted behind the low voltage
compartment. A window is provided in the
low voltage compartment to allow the user to
view the position of the isolation switch before
entering the medium voltage compartment.
