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I.B. 48006
Failure To Unlatch
After making adjustments as outlined in the previous two
sections, operate the contactor electrically. If the trip
solenoid(s) do not unlatch the mechanism:
a: Check voltage applied to the solenoid(s) to be sure it
is within 80% of rated voltage.
b. Check each solenoid coil for continuity. Replace if
burned open. See Table III.
c. Make certain there is an airgap under each solenoid
armature of .120 to .130 inch (3.05-3.30 mm) when
the contactor is latched. If there is no gap, the sole-
noid armatures cannot move to push the latch arm.
Effective 11/97
Fig. 5 Mechanical Latch Installed, 720A Contactor
d. Increase the sensitivity of the latch by loosening the
lock nut on the latch adjustment and tightening (turn
bolt clockwise) one-half turn. Try again, and if
unlatching is not successful, turn bolt another half-
turn, etc., until each solenoid unlatches dependably.
Re-tighten the lock nut.
Failure To Remain Latched
If nuisance unlatching occurs, de-sensitize the latch
adjustment as described under Failure to Latch.
Page 7
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