Noisy Motor Starters

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delectric123

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South Dakota
I often run into NEMA Motor starters and definite purpose contactors that are annoyingly loud when energized. With definite purpose contactors, I've had pretty good luck cleaning the iron cores where they contacted. Right now I have a Square D NEMA 0 Motor Starter that's loud. I tried cleaning the iron cores but it seems that it didn't improve.
any ideas how to get it quiet?
 
Some information on the purpose of the shading coil on a contactor core -

A shading coil is a single turn of conducting material (generally copper or aluminum) mounted in the face of the magnet assembly or armature. The alternating main magnetic flux induces currents in the shading coil and these currents set up auxiliary magnetic flux which is out of phase from the main flux. The auxiliary flux produces a magnetic pull out of phase from the pull due to the main flux and this keeps the armature sealed-in when the main flux falls to zero (which occurs 100 times per second with 50 cycles ac). Without the shading coil, the armature would tend to open each time the main flux goes through zero. Excessive noise, wear on the magnet faces, and heat would result.

I won't name the source or how much to trust that information, but I think it is good information, there could be additional benefits not mentioned.
 
Additionalred;1569184]Some information on the purpose of the shading coil on a contactor core -

A shading coil is a single turn of conducting material (generally copper or aluminum) mounted in the face of the magnet assembly or armature. The alternating main magnetic flux induces currents in the shading coil and these currents set up auxiliary magnetic flux which is out of phase from the main flux. The auxiliary flux produces a magnetic pull out of phase from the pull due to the main flux and this keeps the armature sealed-in when the main flux falls to zero (which occurs 100 times per second with 50 cycles ac). Without the shading coil, the armature would tend to open each time the main flux goes through zero. Excessive noise, wear on the magnet faces, and heat would result.

I won't name the source or how much to trust that information, but I think it is good information, there could be additional benefits not mentioned.[/QUOTE]

Additional benifits were worn parts on the holding contact block, and springs for the main contacts that had noticeably reduced tension. It did not appear to have suffered from heat stress yet. Started, locked in, and motor ran.
 
There are two main causes for noisy contactors: debris on the pole faces of the armature such as drill shavings, bug bodies or even rust, or a broken/missing shading coil. You have already eliminated one. When you pull the pieces apart like you did to clean then, you MIGHT be able to notice the missing shading coiorotund if it is severely broken. But the effect is still there even if it is only cracked, which you may not be able to see. You might however see the effects of it as a discoloration or even carbon evidence near the crack. On NEMA contactors like that you should be able to buy just that iron core yoke assembly as a replacement part. Loose laminations are a possibility, but I have never seen that on a NEMA or IEC contactor, only on DP contactors (because they are all about how cheap they can be).

As to cause, if it's really old, then "stuff" happens. If it isn't very old, then look into whatever is controlling it. You might have some contact bounce or hysteresis chatter in the control circuit that is making the contactor then chatter, which can cause that to break as well as be causing other damage.
 
Jraef said:
There are two main causes for noisy contactors: debris on the pole faces of the armature such as drill shavings, bug bodies or even rust, or a broken/missing shading coil. You have already eliminated one. When you pull the pieces apart like you did to clean then, you MIGHT be able to notice the missing shading coiorotund if it is severely broken. But the effect is still there even if it is only cracked, which you may not be able to see. You might however see the effects of it as a discoloration or even carbon evidence near the crack. On NEMA contactors like that you should be able to buy just that iron core yoke assembly as a replacement part. Loose laminations are a possibility, but I have never seen that on a NEMA or IEC contactor, only on DP contactors (because they are all about how cheap they can be).

As to cause, if it's really old, then "stuff" happens. If it isn't very old, then look into whatever is controlling it. You might have some contact bounce or hysteresis chatter in the control circuit that is making the contactor then chatter, which can cause that to break as well as be causing other damage.
Click to expand...

Its about 8 yrs in service with a mild load. Is energized about 90% of the time, still looks in next to new condition outside, though there is slight film of ?dust? on its mechanisms inside. there's an identical one next to it with the similar amount of hours that's as quiet as can be. Core laminations are excellent condition. I'll check the mentioned part for a crack.
I didn't find any troubleshooting documents at www.Schneider-electric.com
 
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Since you have an identical one that is quiet, you could switch parts one at a time.
 
Check the shading poles and see if they might be loose in the slots. This can give you a buzzing noise. You can take some silicone and place it into the slots, let it dry, and see if that removes some of the noise. Take care and don't get any on the armature face. One thing that has worked in the past has also been to flip the movable armature. This will sometimes help to remove the noise. You might also want to check the coil and make sure that it is not cracked.
 
delectric123 said:
Its about 8 yrs in service with a mild load. Is energized about 90% of the time, still looks in next to new condition outside, though there is slight film of ?dust? on its mechanisms inside. there's an identical one next to it with the similar amount of hours that's as quiet as can be. Core laminations are excellent condition. I'll check the mentioned part for a crack.
I didn't find any troubleshooting documents at www.Schneider-electric.com
Click to expand...
Here is a picture a picture of the actual Sq. D contactor component.
222941-3.jpg
The shading coils (rings) are the inset oval wires embedded in the ends.
 
Jraef said:
Here is a picture a picture of the actual Sq. D contactor component.

The shading coils (rings) are the inset oval wires embedded in the ends.
Click to expand...

Notice that a jraef said initially, and you can now see in the photo, the shading coils only encircle part of the pole piece ends. That way, similar to using a phase shifting capacitor on a dual tube fluorescent to reduce strobing, there is always a magnetic field at the pole in either the center section or the edge section at any given time.
The slight IR loss in the rings is a small price to pay for the increased holding force with minimal vibration.
I suspect that if even one of the rings were missing, you would get vibration at that end.
 
GoldDigger said:
Notice that a jraef said initially, and you can now see in the photo, the shading coils only encircle part of the pole piece ends. That way, similar to using a phase shifting capacitor on a dual tube fluorescent to reduce strobing, there is always a magnetic field at the pole in either the center section or the edge section at any given time.
The slight IR loss in the rings is a small price to pay for the increased holding force with minimal vibration.
I suspect that if even one of the rings were missing, you would get vibration at that end.
Click to expand...
Doesn't even need to be completely missing, it can be just broken, which can make its field discontinuous.
shading ring.gif
 
Checked out the starter today. Visually inspecting the shading coils, they are in excellent condition. Then i swapped that part Jraef showed an image of, with the other starter, then the other starter became noisy, put it back to the original starter, then that starter became noisy. So that part is the culprit, Its not horribly loud, just unusually louder drone than normal. Must be the nature of the beast:huh:.
 
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