Allis-Chalmers MA-150, Instruction Book

Page: 27 / 48

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A I ignment is checked and adjusted on each phase separately. Be sure
there are no binds between contacts (3-1 I ) preventing proper wiping
action with the disconnect arms.
Attach arcing contact (3-10) to yoke (3-2), if detached, but check
contact lead (section 4.7), before attaching I ink (1-47) to disconnect
arms (3-18) and (3-19).
4.7 CONTACT LEAD (Fig. 3)
Contact lead is adjusted on breakers in the factory and should
normally not require further adjustment. It should, however, be
checked on each phase separately and only with contact alignment on
the phase in correct adjustment (�section 4.6).
The arcing contacts (3-9, 10, 27, 28) should ''make11 before the marn
contacts. Measure and adjust each phase separately as follows:
If
not already detached, remove pin (1-46) to detach I ink (1 -47) from
disconn�ct arms (3-18) and (3-19). Move the disconnect toward the
closed position unti I the arcing .contacts just touch (See Fig. 3,
View A-A, arcing contact engaging.)
The shortest gap between the bottom contact fingers (3-1 I ) and the
contact on the disconnect arms (3-18) and (3-19) should be 7/32 to
1/4 inches. (Dimension b in View A-A of Fig. 3.) Adjustment is made
by opening or closing th; gap with nut (3-1).
Reconnect I ink (1-47) to disconnect arms (3-18) and (3-19) using pin
(1-46).
4.8 CONTACT STROKE (Fig. 3)
Contact stroke should be checked and adjusted only when the contacts
are in proper alignment (see Section 4.6).
In order to ensure proper wiping action and contact pressure, the
stroke of the disconnect must be maintained in proper adjustment.
Check and adjust as follows:
With the breaker latched, dimension a in View A-A of Fig. 3, on the
top pair of fingers should be 1/8 to-3/1611• Adjustment is made with
the breaker in the open position by increasing or decreasing the
effective length of link (l-47) by means of nuts (l-10). Each phase
is adjusted individually.
Trip the breaker open and check to see that dimension d is 4
+
l/8
inches on the 5 kv, and 6
+
1/8 inches on the 15 kv on-all three phases.
(On breakers with more than four contacts per phase, dimension d is
stil
1
measured to the second from top contact.)
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