Temperature, Humidity, and Motor Failure

[Steventyj]

I am working on a maintanence/reliability team and I am setting up a database to track motor failures. I was considering tracking the temperature/humidty of the area where a motor fails but I am not sure of the benifits that would have. Any comments on if we will find a direct link between the temp/humidity enviroments we operate our motors in and their failure rates?

Thanks,

Steven

 

[DanDel]

Temperature: Definitely. Excessive heat will reduce insulation life.
Humidity: Possibly, if the motors were not run very frequently. Normal operating heat will do a decent job of removing most moisture from the insulation.

 

[DougMSOE]

There are 3 failure mechanisms that cause insulation failure
Chemical (aka thermal)
Mechanical
Electrical
Track the failures from when the winding was new (day 1)
watch the motors through their normal operation.
In the mean time read up on statistical models in engineering, reliability and track the failures using the Weibull distribution.
This works very well.
If possible you may also have past failure data that you might extract more data to give you a running start.

 

[electricpete]

Sure that may be useful info.

Humidity may challenge a motor somewhat, particularly if it spends a lot of it's life off (not running) and is not equipped with space heaters. One cue that humidity may have contributed will be if the motor fails shortly after starting.

For a motor which runs 24-hours a day the heat of the motor should be enough to keep windings dry. Also large motors often have space heaters wired in which come on automatically when the motor turns off.

Ambient temperature would have some effect on life of the motor in combination with loading (which contributes to the heat rise) as well as area cleanliness (oil and dust can get in a motor to clog cooling passages and make it run hotter).


I would think in an ideal world you want to gather as much info about each motor failure as possible. Preferably do a post-mortem examination of the failed motor for clues.

Some other interesting pieces of info would be motor frame temperature during operation, and motor load (measured by clamp-on ammeter) during operation.

 

[EdDanzer]

My bad experience with motors that sit is that the insulation picks up moisture. This burnt up a 40hp spindle drive on a machine tool. After megging the motor it was determined it needed drying out. This was a TEFC fan cooled motor

 

[GusD]

A few years ago,our reliability group evaluated the need to monitor Temp/Humidity and correlate with motor failures.We were concerned with Generator/Commutator flashovers in Draglines.We did not pursue this option.
On all our outdoor conveyors(large wound rotor motors)I do know that environmental conditions directly affect motor failures. Wound rotor slipring flashovers .
Over 20 years of operation, our motor failure ratio is at least 5 to 1.We lost 5 motors between the months of Oct/March versus ,1 motor from April to Sept.
We are located in the Northern part of Canada,where winter temperatures range from 0 C to 40 C (40 F) plus.
Quite drastic temperature changes from Winter to Summer. GusD

 

[jbartos]

Suggestion: Visit

http://www.reliance.com/prodserv/motgen/c7090/

etc. for more info
If the motor design basis includes correct values for temperature ranges and humidity ranges, then the motor should have life expectancy within those parameters. For example, there are motors driving pumps submerged and have their life expectancy available from the manufacturers. Motors as any other equipment can be manufactured for harsh environmental conditions.

 

[induction]

temp/humidity enviroments it depends on the motor design shut downs would be the time that air born materials would affect them. Check with the manufacture proper application wash down duty in wet areas hi temp duty ect. If they fit the application testing temp/humidity may only yield small results, but these tests maybe enough to look into the unit further. Check with the manufacture.