What's Causing My 3HP Motor to Fail After 10 Years?

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Discussion Overview

The discussion revolves around the failure of a 3HP motor after 10 years of continuous operation. Participants explore potential causes of the motor's failure, symptoms observed, and considerations for maintenance or replacement. The scope includes troubleshooting, mechanical issues, and general motor maintenance knowledge.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant describes symptoms of the motor failing to start and suggests that issues may relate to brushes or bearings, noting that the bearings squeak.
  • Another participant mentions the possibility of overheating and insulation melting, indicating that it can be difficult to pinpoint the exact issue.
  • A suggestion is made that the start capacitor could be failing.
  • Concerns are raised about the potential fire hazard due to the motor's issues and the tripping of the GFCI.
  • One participant questions whether it is more prudent to repair the motor or to purchase a new one, seeking information on common motor failures.
  • Clarification is provided about the operation of GFCI devices, explaining their function in relation to ground faults.
  • Another participant suggests cleaning the motor and examining the brushes and bearings, indicating that squeaking bearings may need replacement.
  • There is a request for more information about the type of motor (single phase, AC or DC) to provide better answers.

Areas of Agreement / Disagreement

Participants express various viewpoints on the potential causes of the motor's failure, with no consensus on a single issue. Multiple competing theories about the motor's condition and maintenance options remain unresolved.

Contextual Notes

Some participants note the importance of cleaning the motor and examining specific components like brushes and bearings, but there is uncertainty regarding the exact nature of the failure and the implications of the GFCI tripping.

Who May Find This Useful

Individuals interested in motor maintenance, troubleshooting electrical equipment, or those facing similar issues with aging motors may find this discussion relevant.

optimizer
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Hi,
I have a 3HP motor running continuously. After about 5 years it has stopped, flicked breaker and it continued. That happened a few times. More recently, now 10 years, it stopped and wouldn't start. I tried a few things, but turning the motors shaft seemed to get it to work when power was restored. I tried that method again when it failed a number of times, but each time it seemed harder to re-start. It failed again, but this time it doesn't want to start.
What is likely wrong with the motor that causes these type symptoms? Brushes? Some other item in the motor? The bearings squeak a little so I'd wondered if they would stop it, but the shaft has always rotated, so it mustn't be the reason for it not re-starting (even if it may make the motor fail if overheated/seizing while running).
I'd like to get an idea of what normally goes wrong/symptoms/troubleshooting in motors, and which parts age/would be best replaced on an overhaul after 10 years, even if they are still working, but are likely to fail because of the motor age.
Thanks.
 
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I don't know enough about motors to help you, other than suggesting a good cleaning if possible. Any motor in my place would have half a pound of cat hair in it after 10 years. :biggrin:
I would urge caution if you're continuing to use it. Sounds like a possible fire hazard to me. The tripping of breakers is not a good sign.
 
They can overheat and melt insulation, gather gunk, etc. Tough to know exactly what it is. But for the price of a 3hp motor (compared with what you are paying to run it), why bother trying to fix it?
 
Last edited:
The start capacitor could be going bad.
 
Mouse/Rat fur more like.

Well that's the thing, I'm not sure if it's better to service the beast or buy new. If I had more of an idea of what genrally goes wrong with motors (there's probably not very much to them), and if a simple repair can give it a continued long life, I could make a better decision.

Are there any sites or books you know of that provide "Electric Motors for dummies" type info?

Thanks for the info Phrak. The searches I made before posting came up with "start capacitor".

Actually, I'm not sure it's throwing a breaker. It's on a GFCI, and I'm not sure how they work. Are there just 2 positions the red button can be in "in-on" and "out-off", or can it position itself between the 2? It seems to push in a little from what looks like the "in-on" position.

When you press the other button "the test button", does that switch the power off, or is it still allowing power to the device?

Thanks
 
A GFI is similar to a breaker, except that it's triggered by a ground fault rather than an overload. If the returning (neutral) line shows less current than it should, the device assumes that there's something wrong and trips. The test button is just a simulation system so you can make sure that it's working properly. There is no 'half-way'; it's either on or off.
 
If you're tripping a GFI, you've most likely got some old insulation/mouse hair/grease/general gunk leaking to earth. Is this 230 VAC, single phase?

First thing I'd do is clean it really well, then examine the brushes (10 years continuous!), and then lubricate the bearings, although if the bearings squeak, that's a bad sign and they probably need replaced.

Why do you have it on a GFI? And, what kind of GFI?
 
optimizer said:
Hi,
I have a 3HP motor running continuously. After about 5 years it has stopped, flicked breaker and it continued. That happened a few times. More recently, now 10 years, it stopped and wouldn't start. I tried a few things, but turning the motors shaft seemed to get it to work when power was restored. I tried that method again when it failed a number of times, but each time it seemed harder to re-start. It failed again, but this time it doesn't want to start.
What is likely wrong with the motor that causes these type symptoms? Brushes? Some other item in the motor? The bearings squeak a little so I'd wondered if they would stop it, but the shaft has always rotated, so it mustn't be the reason for it not re-starting (even if it may make the motor fail if overheated/seizing while running).
I'd like to get an idea of what normally goes wrong/symptoms/troubleshooting in motors, and which parts age/would be best replaced on an overhaul after 10 years, even if they are still working, but are likely to fail because of the motor age.
Thanks.

Is this a single phase motor? Is it an AC or DC motor? More information about the motor would help you get a correct answer.

CS
 

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