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Old 09-23-2016, 09:33 PM   #21
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So does the coil still have voltage the whole time it is dropped out until it restarts?

I would have said bad aux contacts if you hadn't said the power stays on to the coil.

Check the shading coils on the armature. If they are loose or broken it could cause problems. If all else fails change the coil and armature.
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Old 09-24-2016, 11:49 AM   #22
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Quote:
Originally Posted by Jhellwig View Post
So does the coil still have voltage the whole time it is dropped out until it restarts?
Yes


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I would have said bad aux contacts if you hadn't said the power stays on to the coil.
We checked that first


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Check the shading coils on the armature. If they are loose or broken it could cause problems. If all else fails change the coil and armature.
Checked that 3rd or 4th and did not appear to be an issue
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Old 09-24-2016, 12:39 PM   #23
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Where did you reference your tester to when you hooked to it? Both terminals on the coil or the neutral somewhere else in the panel? Could be a bad overload block.
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Old 09-24-2016, 12:46 PM   #24
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The problem is voltage on a closed field winding looks exactly like voltage on an open field winding. I think current would be the only way to prove the circuit.
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Old 09-24-2016, 06:45 PM   #25
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The problem is voltage on a closed field winding looks exactly like voltage on an open field winding. I think current would be the only way to prove the circuit.

When Our guy discovered it was most likely the coil he monitored voltage and current at the coil.
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Old 09-24-2016, 06:51 PM   #26
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When Our guy discovered it was most likely the coil he monitored voltage and current at the coil.
So, did he see the coil circuit drop out or not?
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Old 09-25-2016, 09:42 PM   #27
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Quote:
Originally Posted by Brain John View Post
We did coil voltage was present coil dropped out, cools off and automatically restarts
If the voltage applied to the coil stays at the coils rated voltage, I would suspect the coil and change the coil or contactor.

Monitoring the coil current during failure as mentioned earlier could also show it drop, but I'd like to see the voltage on the coil at the same time.

Automatically restarting concerns me. Normally when a starter shuts down it doesn't restart until something orders it to start (Operator / PLC / etc...)
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Old 09-25-2016, 09:45 PM   #28
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Can you supply the Make/Model of the starter? All suggestions are valid but I'd like to see a wiring diagram as I don't understand why it "automatically restarts".
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Old 09-25-2016, 09:47 PM   #29
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Oops, I see your comment about autorestart in the program, I missed that earlier.
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Old 09-25-2016, 10:15 PM   #30
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Quote:
Originally Posted by splatz View Post
(Note: uninformed question follows, not the helpful suggestion you were probably hoping for.)

I don't know much about infrared, although I am planning to learn more. Do you break out an infrared camera and set it up and take video on this kind of thing? See if the contacts of the starter heat up over time, or maybe some connection is intermittent, or some other hotspot develops under certain conditions?

I have to admit I'd like to do this 50% because it seems like a useful tool, 50% because it would be a real cool gadget and impress the Shiite out of customers. Maybe 49%-51%.
With limited experience using IR camera's they are more suited for finding bad connections on buss's and such. A simple hand held IR sensor would tell you if equipment is out of range much easier and cheaper. Trying to spot a hot spot inside a coil, inside a contactor isn't easy, if not impossible.
Hand Held IR Sensor's
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Old 09-26-2016, 11:02 AM   #31
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without having a baseline for what a healthy coil is supposed to be reading (in regards to current) then may be hard to determine if there is or isn't an issue with the shading coil.

Like what was previously said, the shading coil may be degraded, hindering its ability to spread the magnetic pull across the entire the entire armature, (over time).
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Old 09-26-2016, 11:09 AM   #32
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meanwhile, having lost valuable time and money while other companies are trying to figure out what is going wrong, the customer flew in ACME Electric at great expense (All the way from Honolulu) who ripped the old equipment out and replaced everything with brand new in a single 8 hour shift and it is all working just fine now...............................

Man those private jets sure are expensive....
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Old 09-26-2016, 02:33 PM   #33
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Quote:
Originally Posted by Moonshot180 View Post
without having a baseline for what a healthy coil is supposed to be reading (in regards to current) then may be hard to determine if there is or isn't an issue with the shading coil.

Like what was previously said, the shading coil may be degraded, hindering its ability to spread the magnetic pull across the entire the entire armature, (over time).
Okay.... I'm retired but still getting educated....

If the shading coil was bad, wouldn't the coil make an obviously loud buzzing? Correct me if I'm wrong but isn't a shading coil just a heavy ring of copper wrapped around some part of the laminations of the contactor to create a "2nd-phase" to prevent the magnetism from dropping to zero during the AC's Zero-Voltage point?

If the shading coil was open there should be chatter. If it open's due to heat, then it should start to chatter after the heating period. I wouldn't expect it to drop the contactor out but when it starts chattering it may cause something else to drop it out, like excessive current on the motor due to the chatter, if it's severe enough.
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Old 09-26-2016, 04:21 PM   #34
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I wouldn't say it could be open, only that there may be degradations within the coil. I agree that if that there would be chatter and/or immediate failure of the contactor pulling in if the shading coil was open.

I am not retired, but I am still learning, & I am always open to constructive criticism. I try to stay humble. My description of the shading coil, was a general description. I agree and understand the science behind it. In the future, I can describe as saying that the shading coil maintains an average magnetic field across the coil to ensure the armature is held in while the contactor coil is energized.
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Old 09-26-2016, 04:26 PM   #35
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You say "may be degradations".

Let's explore that. What I remember of shading coils is that they are usually a heavy copper coil.

Faults:
1) Open.
2) Loosened somehow but still closed.

What other types of degradation can we have, other than dirty laminations which is more an armature/stator fault.
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Old 09-27-2016, 07:56 AM   #36
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Good point AWW. Hard to imagine it being open, considering the size of them (typically).

Loose? Or maybe it's missing one..

I do like your other option of an issue with the laminations of the coil itself. Something is going on in there to degrade that magnetic field.
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Old 09-27-2016, 11:49 AM   #37
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Quote:
Originally Posted by Moonshot180 View Post
Good point AWW. Hard to imagine it being open, considering the size of them (typically).

Loose? Or maybe it's missing one..

I do like your other option of an issue with the laminations of the coil itself. Something is going on in there to degrade that magnetic field.
I am glad you guys bring up few items .,,

There one item I almost forgot for many years I should know this one better but anyway.,,

but a wild guess but it did happend before did the phase conductor got too close to the coil ?? it may cause oddball magatanic signture or something like that cause the coil get overheated and drop out.

but a hidden crack on lamation plates can cause this too..
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