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Moving Contact
Arm
Figure 6. Removing moving contact.
Figure 7. Removing stationary contact.
Contact resistance*
Standard: 750-875 mΩ
Contact Retaining
Screws
Extra Creepage (17 inch): 875-1000 mΩ
20 kV (125 kV BIL): 845-945 mΩ
Moving contacts
Minor pitting can be smoothed with crocus cloth. If contacts
show appreciable wear due to arc erosion, replace as
follows:
1.
Contact Bar
2.
Stationary contacts
Smooth minor pitting with crocus cloth. If contacts are
excessively eroded, replace as follows:
1.
2.
Stationary Contact
3.
Assembly
4.
Contact Retainer
N
Contact Stud
Be sure not to pull contacts or contact structure out
Flexible Contact
of alignment when tightening the jumper lead to
Lead
the bushing terminal rod. To test alignment, wet the
contacts with oil. Then, with the actuator mechanism
prepared for a closing operation, push the contacts
closed by hand and hold for a few seconds. When the
moving contacts are released, they should be pulled
open by the spring in the head mechanism. If not,
adjust stationary contacts as described in Step 4 until
they do so.
TYPE NR OIL SWITCH MAINTENANCE INSTRUCTIONS MN230001EN February 2016
Remove the round head screws and lockwashers that
secure the moving contact bar to the contact arm.
Remove the bar from the contact arm.
Reassemble the new moving contact bar to the
contact arm and secure with round head screws and
lockwashers. Apply one drop of Loctite
®
242
to each threaded hole of the contact bar prior to
assembly.
Remove hex nut, lockwasher and flatwasher from
contact stud. Loosen nut on bushing rod slightly and
slip terminal lead from contact stud.
Open flexible contact leads and remove contact
retainer. Pull the stationary contact assembly and
contact roller from contact stud.
Install contact roller within new contact assembly and
mount on the contact stud. Install following parts in
order: contact retainer, flexible contact leads, terminal
leads, flatwasher, lockwasher and hex nut. Tighten hex
nut on bushing rod.
With the moving contacts in the open position, the
space between the stationary contacts should measure
0.281 ± 0.010 inch.
ote:
The stationary contact assembly is normally pre-
adjusted during manufacture to obtain this clearance.
Bend the contact fingers as required if this spacing is
not within specified tolerances.
CAUTION
®
Threadlocker
7
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