Failure of Allen Bradley Auxiliary Contact Block #595-AB:1 normally open contact and 1 normally closed used on Nema size 0-4 contactors and starters We appear to have a failure of the normally open contact on some of these units. Is there a small surge suppressor we can use across this contact set to elongate their life? We are only carrying 110v. power to energize an output card point for monitoring the status of the contactor.

Tks.

 

You should be able to just go to DigiKey or the other electronics houses and look for a transzorb rated for 115V and wire it across the contacts. It would be a good idea to look at the contacts to see if they are getting burned. It could be dust or perhaps dry switching, this last is unlikely with 110V. This is an area that is widely neglected these days.

I see very few cases where suppression diodes (DC) or transzorbs (AC) are used to properly protect contacts. They can make a tremendous difference in life and reliability at very low cost.

Regards
cww

 

GMack... Offhand I'd say it is a misapplication but more info is required:

Is the current carred by the contact AC or DC?

Regards, Phil Corso

 

I am not quite sure what it is you are using this for. On the one hand you say you are only monitoring the status of the contactor but you also mention energizing an output card point with it.

I suspect you have misapplied it in some way.