Bypassing & Isolating Operator’s Manual
381333-194 B 15
Bypassing & Isolating
4. Open the lower enclosure door. Pull out both left
and right side rails then use the two tab handles to
roll out the transfer switch. It can be safely
inspected in this position. The transfer switch can
also be removed for easier maintenance operations.
See Figure 19.
Hazardous voltage capable of causing electrical
shock, burns, or death; do not touch any control
circuit terminals
Figure 19. .Transfer switch isolated
and pulled out for inspection.
See page 10 for maintenance handle use. A lifting yoke
734408 is available to facilitate lifting by using an
overhead crane or similar equipment. See WARNING
The Transfer Switch weighs 165–235 lbs.
depending upon the number of poles. Use lifting
device 734408 or other device capable of lifting
this weight to avoid personal injury or equipment
damage. Two persons are recommended
Contact Inspection
The main contacts are protected by arcing contacts. The
arcing contacts make first and break last to avoid arcing
at the main contacts. Contact condition should be
checked annually. Contacts should be replaced when
contact material becomes severely worn. Discoloration is
normal. Do not file contacts because it wastes material.
Instead use light emery paper to clean up the contact
surfaces.
If the contacts need to be replaced see page 10
To prevent the possibility of fatal electrical shocks
and burns, bypass, isolate, and withdraw the
transfer switch before working on it.
The contact assemblies (two for each pole) are located
to the right of the operator mechanism.
1. Deenergize transfer switch (pages 12 thru 15)
Bypass, isolate, and withdraw transfer switch. Use a
voltmeter to verify that no electrical power is present
at the transfer switch terminals.
2. Use the maintenance handle (page 10).
Open the contacts that will be inspected by using
the detachable maintenance handle.
3. Remove the interphase barriers (Figure 20).
Use a blade screwdriver to loosen (ccw) four
round–head screws holding each barrier to the arc
chutes. Slide barrier up until keyholes clear the
round–head screws, then remove it.
Figure 20. Interphase barrier removal
4. Remove the arc chutes.
Use a 5/8” nutdriver to remove (ccw) two long
insulator nuts. Then pull the arc chute outward
(off the long threaded rods). See Figure 20.
handles
left rail
right rail
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