Motor Insulation Class 1

[Downstream]

I am writing a report about operating temperatures and expected lifespan of a Class F motor. I was looking for a good copy I can insert in my report of a graph that I have seen of winding temperature and insulation life.

Anybody know where a insulation life versus winding temperature graph is posted that is available to use?

If it is in a standard, let me know and I can get the standard.

 

[sreid]

It is generally assumed that wire insulation will have a life of 10 years at rated temperature. As a rough estimate, the life will double for every 10 degree C temperature drop. The reality is that something else will probably fail first.

 

[UKpete]

The formula usually quoted for lifetime of motor insulation (as applied by sreid) is the Arrhenius equation from the field of chemistry, eg see:

http://www.weibull.com/AccelTestWeb/temperature_nonthermal_introduction.htm

http://www.weibull.com/AccelTestWeb/arrhenius_relationship_introduction.htm

http://www.chemguide.co.uk/physical/basicrates/arrhenius.html

http://www.shodor.org/UNChem/advanced/kin/arrhenius.html

There are probably better links than this but there are so many to chose from if you type "arrhenius+plot" into a search engine. If you add the word "motor" you still get a lot of links.

 

[sabap]

check this site:

http://www.usbr.gov/power/data/fist_pub.html

go to keeping motor winding dry

I have seen the graph in one of the articles posted here.

To me the insulation life at rated temperature is 40 years. For motors winding keeping them free of dust, moisture and oil is extremely important.

Check the NEMA website for standard, I think its NEMA MG-1 or 2

 

[electricpete]

I have seen a chart before where the life at rated temperature is 20,000 hrs which equates to 2.5 yrs of operation. It is included in some EPRI documents, but no reference to IEEE is given.

It is based on accelerated life motorette testing. Correlation to actual insulation lifetime in a motor is subjective.

I looked at a few IEEE standards and couldn't find it the graph. One I could locatewas IEEE-1. You might look at that if you have access.

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[DougMSOE]

What you are looking for is,
Temperature Vs Life (Figure 3) in IEEE117 and 101.
If you can't get a copy, send me your fax or email and I'll send you one.

 

[jraef]

The "rule-of-thumb" I have heard most often repeated is "for every 10deg C rise above the limit, insulation life is halved" as found in this article:

http://www.ecmweb.com/mag/electric_understanding_modern_motors/

... and repeated in this one:

http://www.mt-online.com/articles/0704easa.cfm#table1

There is also a promising graph on page 10 of this PowerPoint presentation, but it doesn't show a source.

http://baen.tamu.edu/users/stark/AGSM325_files/Lecture/6B Motor Nameplate Lecture.325.pdf

"Venditori de oleum-vipera non vigere excordis populi"

 

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