SECTION 8-Contact Maintenance (Cont.)
8.3
CONTACT ADJUSTMENT
AKR
50/SOH
&
AKRU
50
The contact structure shown in Fig. 47 is used by all
AKR50 breaker types. This structure uses two movable
contact arms. Each arm acts against a stationary arcing, a
stationary i ntermediate and three stationary mains.
The following procedure is used to perform the wipe ad-
j ustment.
1 . Open the breaker, remove arc quenchers.
2 . Arrange the breaker for slow-closing.
3. Select one pole of the breaker and place a thin sheet
or strip of tough insulating material, such as mylar, over the
stationary arcing and intermediate contacts. This strip
should be about two inches wide and must prevent the
arcing and intermediate contacts from making contact
when the breaker is closed.
4. Using the ratcheting_maintenance handle, slow-close
the breaker with the insulation held in place. Examine the
i nsulation to make sure it "over-hangs" below the in
termediate contacts, but not enough to cover the main con
tacts.
5. Attach a conti nuity checker (bell-set, light, or ohm
meter) between the upper and lower stud. The checker
should indicate continuity exists.
6. Facing the breaker, turn the wipe adjustment stud
shown in Fig. 47 clockwise until the checker i ndicates that
the main contacts are separated.
7. Turn the stud counter-clockwise until the main con
tacts just touch.
8. From this point, advance the stud counter-clockwise
270 degrees. This will be 4-1/2 flats.
9. Once the adjustment is complete, verify that the torque
required to j ust turn the adjustment nut is greater than 40
in-lbs. If less torque is required, carefully add LOCTITE 220
or 290 to the adjustment nut threads. Wipe off any excess
LOCTITE. Once the LOCTITE is set, recheck the torque
valve.
1 0. Trip the breaker, remove the insulating strips.
1 1 . Repeat the above procedure on the other two poles.
FIG. 47
-
1 600
AMP CONTACT STRUCTUR E
36
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