Allis-Chalmers MA-150, Instruction Book

Page: 25 / 48

4.S CONTACT PRESSURE OF HINGE JOINT (Fig. 3)
The hinge joint contact pressure is in proper adjustment when a pul I
of from 7 to 9 pounds on the S kv, and from S to 7 pounds on the IS kv
is required to move the disconnect toward the open position. This
measurement is obtained as follows:
Remove pin (1-46) and detach link (l-47) from the disconnect arms (3-18)
and (3-19). Move the disconnect to a position just short of 11contact
make11• Attach a spring scale to the disconnect 8-1/2 inches on the 5 kv,
and lO-I/2 inches on the
IS
kv, above screw (3-24), and in a direction
perpendicular to the longest edge of the disconnect arm. Measure the
pul
I
to move the disconnect toward the open position.
Adjustment is made by tightening (or loosening) nut (3-14).
Before attaching link (l-47) to disconnect arms (3-18) and (3-19), check
contact alignment (section 4.6) and contact lead (section 4.7).
4.6 CONTACT ALIGNMENT (Fig. 3)
The contacts are an integral part of the bushing assemblies and are
carefully aligned with the upper and lower bushings before shipment and
no further adjustment should normally be necessary.
The horizontal pairs of main contact fingers in each phase should 11make11
with the moving contact simultaneously. (Note: Contacts on different
phases should not necessarily 11make11 simultaneously, they can vary as
much as 1/32 inches.)
If not already detached, remove pin (1-46) and detach link (l-47) from
disconnect arms (3-18) and C-19).
On MA-75/1508 and FC-150/250/500 Breakers - Detach arcing contact (3-10)
from yoke (3-2) by removing pin (3-26). Move the disconnect toward the
closed position until it just touches a main contact finger (See Fig. 3,
View A-A, main contacts engaging). Dimension c should then be no greater
than .020 inches, with one contact touching. -
On MA-250/3508, FB-250/500 and FC-7SO Breakers - Remove pin (1-46) and
detach link (1-47) from disconnect arms (3-18) and (3-19) of two phases
only. With the maintenance closing device, move the disconnects of the
remaining phase toward the closed position unti
I
a main contact finger
(3-11) is touched. Dimension c should then be no greater than .020
inches, with one contact touching.
Adjustment is made by loosening two nuts (3-22) and rotating the contact
assembly. Alignment (dimension�) should be checked after tightening
nuts (3-22).
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