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Equipment Description
Figure 5
Eaton Type SL Medium Voltage
Vacuum Contactor 800A
The isolating switch is a non-load break device.
It must never close or interrupt a power
load. Electrical and mechanical interference
interlocks ensure that the contactor is open
before the isolating mechanism can be
operated. However, it does have a limited
capacity for interrupting the single-phase
control power and potential transformers
exciting current. In terms of transformer
ratings, the maximum load is the equivalent
of an unloaded (exciting current only) 6kVA
transformer.
!
WARNING
FlexTrol
™
controllers are sometimes
energized by a back-fed condition that allows
the medium voltage compartment to be
energized with the isolation switch in the
open position. Study the plant single line
diagrams to make certain that no back feed
situation exists before entering the medium
voltage compartment.
!
CAUTION
All power sources must be isolated and locked
out before servicing the equipment.
For applications where the controller is back
fed, the grounding fingers should be removed
from the isolation switch.
The switch consists of a fixed rear portion and
a removable front portion. The fixed portion
includes the controller line fingers and a
moveable shutter that isolates the line fingers
when the switch is in the open position. The
removable portion is operated by a handle
mechanism that extends through the controller
medium voltage door. With the handle in the
up position, the switch is closed and medium
voltage is available for connection to the
controller load. With the handle in the down
position, the switch is open and medium
voltage is isolated from the controller and the
controller load.
An isolation switch viewing window is
provided on the front door of the medium
voltage control compartment. After opening
the isolation switch and before opening the
medium voltage door, the switch should be
visually examined through the viewing window
to verify that it is in the open position. Three
green and white “barber poles” will be visible
when the switch is in the open position and the
shutter assembly is in the isolating position.
The isolating switch handle can be padlocked
in the ON and OFF positions
.
