# Testing a Solenoid Coil



## wendon (Sep 27, 2010)

qitara said:


> Hi Folks
> 
> What is the best way to test a solenoid coil ?
> 
> ...


Are you sure your solenoid armature isn't stuck?


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## quanchai (Jul 13, 2012)

wendon said:


> Are you sure your solenoid armature isn't stuck?


You mean the plunger, its not stuck, even if it was stuck it should not draw that much current

Try to hook it up to an another DC source that has around 50V and se how much current it draws


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## qitara (Apr 26, 2013)

wendon said:


> Are you sure your solenoid armature isn't stuck?


Cant be, because the there is nothing directly attached to the coil


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## dronai (Apr 11, 2011)

Did you test the voltage across the coil when it is actuated ?


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## John Valdes (May 17, 2007)

Using ohms law should tell you if the coil is good.
If the ohm reading is good and you know the coil is bad, it is either your meter or the coil is actually good or cold.
Solenoid coils have a very high resistance in the normal size range. So they should be a very accurate reading. Easy to measure is what I mean.

Take a new coil and measure the resistance vs the suspect coil and see. They both must be at the same temperature.

Personally I just replace the whole solenoid if easy enough. Sometimes the tiniest piece of sand or trash will stop it from working.


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## ScooterMcGavin (Jan 24, 2011)

Is it possible this is an AC coil being used on DC?


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## CYoung (Apr 19, 2013)

scameron81 said:


> Is it possible this is an AC coil being used on DC?


Kinda of what I was thinking.


> Cant be, because the there is nothing directly attached to the coil


Was also wondering about this statement. Should be something through center of coil.


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## pudge565 (Dec 8, 2007)

John Valdes said:


> Using ohms law should tell you if the coil is good.
> If the ohm reading is good and you know the coil is bad, it is either your meter or the coil is actually good or cold.
> Solenoid coils have a very high resistance in the normal size range. So they should be a very accurate reading. Easy to measure is what I mean.
> 
> ...


My boss had me crawling around under a liquid nitrogen truck to trace the airlines to the E-stop solenoid, I figured he had already checked the solenoid itself. He did not turns out it was full of sand from the truck getting sandblasted and rechassied. Spent a whole day chasing my tail.


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## qitara (Apr 26, 2013)

scameron81 said:


> Is it possible this is an AC coil being used on DC?


Its a DC coil


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## uconduit (Jun 6, 2012)

is there a listed current draw specification for the solenoid that you can verify with an ammeter?


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## qitara (Apr 26, 2013)

dronai said:


> Did you test the voltage across the coil when it is actuated ?


Yes, the voltage should go down to around 103vdc from 110vdc, but its getting down to 80vdc when this coil is energized, the system has 5 other coils that are of the same type, non of them produce the same problem where the voltage goes down to 80vdc and causes the indication lamps to dim


Well I have already sent the coil to be rewired but I want to now if there is any way to test the coil like with a megger or something, usually an normal meter wont detect the bad insulations due to the low voltage output the meter produce, so I hope there have to be another way to test


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## Big John (May 23, 2010)

I'd be surprised if you had a turn-to-turn failure that you couldn't see with a standard ohmmeter, I'd really tend to think there was a problem with the coil plunger.


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## oliquir (Jan 13, 2011)

a dc coil is easy to test since there is no inductance like on a ac coil. So you can can just use ohm law to find is current. if it draw more current than spec it is defective


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