problem with chattering contactors for drill press machine

Jun 07, 2006 5 Replies

Need advice:



What are some causes for chattering relays. I have a three phase drill press machine with forward/reversing contactors. It runs in both directions but the contactor for each direction buzzes or chatters rather loudly. I have already checked for loose wires and obvious problems.



Sincerely, steve



voltage measures ok?

measured the amp draw of the coils?

How old are they?

Sounds like a bad contactor, or perhaps the coil's shunt has become dis-engaged, or it could be something blocking the contacts and letting the armature not fully engage.

"the coil's shunt"... oops, I meant the coil's SHADING coil, a small ring like piece of copper that "fills in the valleys" of the incoming AC. On some contactors this shading coil is removable, I would make sure one isnt missing. (Should be one for each coil, forward and reverse).

Dirty pole faces. strip the contactor out and clean the pole faces, probably be as good as new..

sQuick..

buzzing might be loose laminations in the relay coil. annoying but not threatening.

chattering does not sound good. does this mean the drill behaves in a jerky manner in operation?

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