Contactor issues

[Pivotman]

Hello, I am using a ABB contactor as a Master Control Relay. We wired the unit the same as others we have done but the coil overheated and kicked out the contactor after about 2 mins. I replaced the coil and checked the draw of the coil at 4 amps. Does this seem excessive? I can not find any marking other than the 24v 50-60hz rating. The coil is ABB # R81. Any help or thoughts on this would be appreaciated.

 

[itsmoked]

The current draw sounds quite excessive.

The coil could be mis-marked.
Or if the springs in the contactor are wrong and holding the contacts slightly open the coil's current will not drop to its 'sealed' value.

Mess with the contactor by trying to close it harder and see if the current drops dramatically. Do this with the main power OFF. Don't take too long or the coil will fry if this is indeed the issue.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Pivotman]

Itsmoked,
I tested this coil through our switches and with a line straight from our power supply. From your last post I manually pressed the contactor to ensure it was making full contact and it was still drawing 4 amps. I will have to call the manufacturer and see if they have any further details or check if they possibly have a mis labeled batch of coils.

Thanks,

Jason

 

[itsmoked]

We'll be most interested in the results..

Keith Cress
kcress -

http://www.flaminsystems.com

 

[jraef]

Well, coil code 81 is SUPPOSED to be a 24V coil, but depending on the relay / contactor SERIES, it could be 24VAC or 24VDC. If you have a Type A or Type N Series contactor, then it would be an AC coil. If you have an NL, NLZ or TNL Series contactor, it would be a DC coil.

You mention a power supply, so I am assuming 24VDC? If so, and the coil says 50/60Hz, then there is your problem, you have an AC coil on a DC control power system.

If you have an AC control power system, then check the contactor Sieres number to make sure you don't have a DC coil.

And because the contactors are different bases, you cannot swap out an AC coil for a DC coil in the same product Series. If someone tried to do that, there may be a physical interference with the armature.

Get ALL of your numbers together and call ABB.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376

 

[Pivotman]

Jraef you hit it on the head. My supplier spec. the wrong contactor for me. I am not much of a electrical guy and I let my distributor call out my contactor. But he stood behind his work and is paying for his mistake by refunding the contactor I fried and sending me the correct one free of charge.

Thanks for the help.

 

[jraef]

You're welcome, glad it worked out for you.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
For the best use of Eng-Tips, please click here -> faq731-376