8.6
CONTACT REPLACEMENT
AKR 30/30H & AKRU 30
Refer to Stationary Contact Identification, Section
8.5
before replacing any stationary contacts.
The stationary contacts are held in place by the contact
springs which pivot the contacts against the contact stop,
refer to Fig.
45.
To replace contacts:
1.
Remove the arc runner. It is secured by two screws
into the base and one screw into the contact stop.
2.
Release each contact spring by holding the contact,
extending the spring, and removing it from the contact.
The end pieces on each spring have a small hole for inser
ting a spring puller.
A
suitable puller can be fashioned by
forming a hook on the end of a length of
.062"
diameter
steel wire.
A
spring puller is available for this use and may be
ordered under Cat. No.
286A8168G1 .
3.
Clean off the existing lubrication o n the stud's pivot
area. Replace with a small amount of D50HD38 (MOBIL
28)
before installing new contacts.
4.
Torque the upper arc runner mounting screws to
45
±
5
in-lbs. Torque the lower screw to
35-40
in-lbs.
The movable contacts are removed as follows, referring
to Fig.
46.
1 .
Using a right angle tru-arc pliers, remove the tru-arc
retainer on the coupling pin. Drift out the coupling pin.
2.
Remove the pivot pin hardware and spring from one
side of the pivot pin. Carefully remove the pivot pin.
3.
Slip out the contact arm.
8.7
CONTACT REPLACEMENT -
AKR 50/50H, AKRU 50 & AKRT 50/50H
Refer to Stationary Contact Identification, Section
8.5,
before replacing any stationary contacts.
The stationary intermediate and main contacts are
replaced just like the stationary contacts on the
800
ampere breakers. Refer to steps
2
& 3
in Section
8.6
Referring to Fig. 50, the stationary arcing contacts are
replaced as follows:
1 .
Remove the arc runner and the flat insulation
assembled underneath the arc runner. It is secured with
four screws. When removing the lower screws, use care
not to damage or misplace the insulating washer found
under each of these screws, see Fig.
50A.
2.
Remove the arcing contact pivot. Clean off the ex
lubrication found on the
area Replace with
(MOBIL
28),
see Fig.
3.
Remove the Insulating spacers, contact pin and arc-
ing contacts, see Fig.
50C.
4.
Reassemble the reverse of above. Make sure that the
insulating spacers and insulating washers are properly in
stalled. Torque the arc runner hardware to
45
±
5
in-lbs.
The movable contacts are removed in a similar manner
as the
800
ampere breaker movable contacts. Refer to
Section
8.6.
When removing the pivot pin from a 2000
ampere
(AKRT
50/50H) contact assembly, the pivot pin
from the opposite contact assembly must be slightly
removed. This provides enough clearance to completely
remove the pivot pin.
4.
Place a thin film of D50HD38 lubrication on the pivot
surfaces of the new arm. Clean any existing lubrication
�-'�'
from the pivot pin and place a small amount of D50HD38
;;�::,
on it.
• . . ·. _
- .- ·
5.
Install the new arm, insert the pivot pin, and replace .
the pivot
�nd hardware. Tighten the pivot pin hard-
> ·�
·. ·
. ..
..
ware to
±
1n-lbs.
·.
·
FIG.
50A - ARC RUNNER
STATIONARY CONTACT - 1 600/200 AMP
REPLACEM ENT CONTACT STRUCTURE
39
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