hvac contactor

[topgone]

We provide the protection that we are required too, the contacts still fail when they close into a short.

Very true. And I don't know of somebody who can predict when something shorts out.

 

[T.M.Haja Sahib]

..... the contacts still fail when they close into a short.

The contacts are liable to weld perhaps because the existing fault current level at the point they are provided is not taken into consideration.Just a thought.

 

[kwired]

The contacts are liable to weld perhaps because the existing fault current level at the point they are provided is not taken into consideration.Just a thought.

When contacts are no longer anywhere near a like new condition they can weld for just about any reason. The contact surfaces are no longer slightly curved making more contact surface, more arcing when it operates, higher operating temperatures at the contact point. I see more welded contacts in definite purpose contactors even when they were not closed into a short than I do for NEMA or IEC contactors. I would guess there is probably some difference in construction or materials of these contacts, and also has some to do with the reason for the difference in price.

 

[T.M.Haja Sahib]

When contacts are no longer anywhere near a like new condition they can weld for just about any reason.

IMO,they are too old to remain in service....

 

[kwired]

IMO,they are too old to remain in service....

In an industrial plant they may get routine inspections and get replaced at a certain point. That is probably wishful thinking but is about the only place it may happen. In other locations - especially dwellings they have to fail first or no one even knows they are close to needing replacement.

 

[iwire]

IMO,they are too old to remain in service....

You may well be right.

What has that got to do with the OPs question?

 

[jumper]

In other locations - especially dwellings they have to fail first or no one even knows they are close to needing replacement.

:thumbsup:

Heck, as a HO I do even test GFCIs or barely remember to replace batteries in smokes, like I am going to open the outside unit and look at contactor. Not.

 

[templdl]

You may well be right.

What has that got to do with the OPs question?

Re the OP, simple, that's exactly what happened when mine failed, the 1p contacts failed, that is the were so trashed that they wouldn't close and complete the circuit anymore. A simple voltage check from the line to load side of that pole read full line voltage when it should have read zero if the contacts actually were completing the circuit.
To get myself back up in service temporarily I took some 320 to 600 grit wet or dry silicone carbide abrasive paper (used dry) and cleaned the contacts which is usually a no no. But it got me back into service and running allowing me time to purchase a replacement as well as my spare.

 

[iwire]

as a HO I do even test GFCIs or barely remember to replace batteries in smokes, like I am going to open the outside unit and look at contactor. Not.

That is shameful, every Saturday I fully dissemble all my homes electrical equipment to inspect. I will tell you, riveting the breakers back together is a pain in the rear.

 

[jumper]

That is shameful, every Saturday I fully dissemble all my homes electrical equipment to inspect. I will tell you, riveting the breakers back together is a pain in the rear.

ROTFL.:thumbsup:

2 mins later I am still giggling. Thanks

 

[jumper]

In reference to OP, we are very lax in residential testing of components.