I'm out of my element trying to test AC valve coils. Usually, If they fail on me they smoke and crack and smell VERY bad...or, they have no continuity. But, I've had some go bad with none of those obvious symptoms. I Googled and for some of the testing methods you need a magnetomatrix oscifier and capatrometer. There should be an easier way!
inductive ammeter - with AC applied if the coil is conducting at all you should pick up the amp draw.
Compass and switched DC source. Switch so you can cycle the power to the coil. Compass to tell if the coil is generating a magnetic field. (Use a pulsed DC source with a low cycle time for best results)
VOM, non-contact thermometer and the data sheet for the valve. VOM to measure the resistance of the coil. NC Therm. to measure the temperature of the coil. Data sheet to tell you what the correct number should be for a given temperature.
Standard field test is see if an allen wrench sticks to it.
Does it make a difference if the coil is " satisfied" with a core?
Cores won't make much difference for the electrical tests. The magnetic ones could be a problem due to the core retaining magnetism.
But don't ever power one up without the core! That quickly lets out the magic smoke! Paul
If you energize the coil without there being a solenoid inside of it there is a very real possibility that it will overheat and burn in a very short time.
Low voltage DC won't hurt it as long as it's pulsed. The coil will act like a simple choke then.
"PrecisionmachinisT" fired this volley in news:ev2dnXeilve02fHMnZ2dnUVZ snipped-for-privacy@scnresearch.com:
Yeah, the inductance dives toward zero without the iron core in there, resulting in very high current through the coil.
(maybe that should be "with an armature in there", since a "solenoid" is a combination of a coil and an armature )
Lloyd
For testing with a meter, no. But if the coil has an intermittent open, or a thermal open (it quits when it warms up) you almost have to test it in a live circuit.
For testing with live power, if you don't have a valve body and core in the hole the coil will be bad in about three... Two... And there's the smoke - /now/ it's bad.
Don't ask me how I know this.
If you want to disable the valve, you have to pull the wires. Pulling the coil off the valve head is not a good idea.
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Well, a quick-and-dirty tester is to wire a power cord in series with a lightbulb. If they're failed short, the light goes bright and no click of the valve. If they're failed open, the light doesn't light at all. Either way, it doesn't pop a fuse.
You have to size the lightbulb according to the solenoid, to get a really satisfying test, where the valve operates and the light shines (but not full brightness).
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