How often does this happen to you?

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chris kennedy

chris kennedy

Senior Member
Location
Miami Fla.
Occupation
60 yr old tool twisting electrician
Got a call this morning, smoke coming out of motor. Happened to be next door at another facility. Respond to call, insulation test good, ohm readings on winding's all good. Fire it up and bearing smoking like a bitch.

Seems like I am getting a lot of these calls lately where there is a mechanical issue (crank case, bearings) that are none electrical.

You motor guys, we try to educate the end users about likely failures but don't you find it odd they always call us first? Still pays but my time could be better spent elsewhere.
 
chris kennedy said:
Got a call this morning, smoke coming out of motor. Happened to be next door at another facility. Respond to call, insulation test good, ohm readings on winding's all good. Fire it up and bearing smoking like a bitch.

Seems like I am getting a lot of these calls lately where there is a mechanical issue (crank case, bearings) that are none electrical.

You motor guys, we try to educate the end users about likely failures but don't you find it odd they always call us first? Still pays but my time could be better spent elsewhere.
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It happens to us DAILY.
Everyone seems to call the utility no matter what the issue is.
 
I’ve had to paddle out to a sewage pond aerator, to find out maintenance never greased the motor bearings in years. Lucky for them, I was able to grease the motor, and everything started working normal again.
 
hillbilly1 said:
I’ve had to paddle out to a sewage pond aerator, to find out maintenance never greased the motor bearings in years. Lucky for them, I was able to grease the motor, and everything started working normal again.
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Sounds like a job they'd rather have you do, than have to do it themselves. ;)
 
Is there a VFD involved?
If so, likely motor NOT designed for VFD operation.
Hook a VFD to common ac induction motor not designed for VFD operation (especially if long lines from VFD to motor) and the high frequency currents coupled from rotor thru case thru the bearings damages bearings. LOTs of IEEE papers on the phenomenon around 25 to 30 years ago describing the mechanisms and shortened bearing life.
 
It's always the electrical/controls/instrumentation at fault, NEVER the mechanical. Operators tell me a flow meter is broken because they aren't seeing any flow while the pump is on. Drive shaft is verified to be spinning. Turns out the rotor coupling had fractured and wasn't actually turning the rotor. I could go on and on. People tend to blame what they don't understand.
 
So do what needs doing, and bill for it.
ptonsparky said:
... you can overtighten V-belts ...
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You can undertighten them, too.

Did that on a power-steering belt. The driver couldn't perceive when the overpressure valve opened, and couldn't be persuaded to stop turning the wheel to the hard stops. After undertightening the belt, it would slip and squeal when it was hard over.

Can't do that today, with everything driven by a single serpentine belt maintained under perfect tension.
 
oldsparky52 said:
You call the electrician first because electricians know more about other stuff that other stuff people know about electrical.
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Yep. ALL problems are electrical until proven otherwise. We are the go-to guys when a machine doesn't work.

I'm involved in one right now. The GC bought a pump on his own and had us supply a VFD for it. The pump cannot move enough water, so it is MY problem because "The VFD is not programmed right". The VFD is running at 100% speed...
 
"It was an electrical fire."
"How do you know?"
"We can't think of anything else."
"But the power was off to the building."
"Well, there you are."

:D
 
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