Maintenance; Pole Unit; Contacts; Maintenance Of Contacts - Westinghouse DB-50 Instructions Manual

POLE UNIT

E ach pole unit is mounted on a separate
molded base through which the breaker
studs pass. (See Fig. 3 .) The molded bases
are attached to the steel mounting panel and
provide insulation for the breaker studs.
The upper stud and contact are attached
to the molded base by two bolts . The moving
contact is pivoted on the molded base and
attached to the cross bar through insulating
links . The series coil and lower stud are
fastened to the molded base by four bolts .
,_pontacts . (See Fig. 3.)
The DB-50 arcing contact should touch first
on closing, open last on opening. Contact
pres sure on the mains is maintained by ad­
justing gap G to be . 0 78-.093 inches . This
gap is adjusted by removing the cross bar
and screwing the insulating link in or out
on the stud. Be sure to tighten the lock
nuts after each adjustment.
Do not over-adjust as this will cause the
contact springs to compres s to the solid
position and thus increase the closing
effort. Check for over-adjustment by prying
the stationary arc t i p s open t o at least
1 / 16-inch gap.

Maintenance of Contacts .

Rough or high spots should be removed
with a file or sandpaper.
arcing contacts , open the breaker , remove
the arc chutes and then the stationary arc­
ing contacts . C lose the breaker and remove
the moving arcing contacts . The new con­
tacts can then be added in the reverse
order.
CAUT ION: All power shou ld be removed when
changing, maintaining or adjusting contacts.
OPE RATING MECHANISM
The operating mechanism (see Fig. 3) is
non-adjustable and consists of a series of
PART 3 - MAINTENANCE
non-ferrous links designed to secure low
closing and tripping forces . To check for
friction, raise the trip bar and slowly rotate
the manual operating handle in close di­
rection. The linkage should follow the handle
without sticking.
on the handle shaft, the roller lever roller,
and the latch plate at the factory.
C LOSING SP RING ASSEMBLY
The closing spring assembly is shown in
Fig. 3A.
raises the lift link and lower spring guide
to compress the closing spring. Near the
end of the closing stroke the top end of the
lift link strikes the first toggle lever to
start the br � aker closing. As the breaker
closes, the push rod raises the toggle link
and push link out of the toggle which permits
the closing spring to complete the breaker
closing.
contact sequence can be obtained by exerting
a slight closing pressure on the clos ing
handle and simultaneously pushing forward
on the breaker cross bar to start the breaker
closing.

Maintenance

To replace the
Oil the pins and slides every 10 , 000 op­
erations .
C LOSING SOLENOID
The closing solenoid (see Fig. 14) is non­
adjustable .
duty only. Check for loose bolts .
Disconnect closing coil leads from control
circuit wiring. Take off bolts {9) , washers
{12) , relay release arm {8) , bolts {10) ,
washers (11) and plate {2) .
coil (7) with brass tube {5) .
A small quantity of lubricant is placed
Rotating the closing handle clockwise
Slow emergency operation to check the
It is designed for intermittent
To remove closing coil, trip breaker.
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Drop closing