generator temp rise

[cvirgil]

with a standby application, is it typical to use a temp. rise of 105 deg. C or 130 deg. C? We are concerened with the heating affects of harmonics and are considering specifying a low temperature rise for the alternator.

 

[electricpete]

Specifying a rise doesn't buy you much unless you also specify the insulation class.

Some people in attempt to gain thermal margin will specify that the machine be limited to a rise one insulation class below the actual insulation class of the machine.

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[ScottyUK]

Typical spec would be to insulate the machine for temperature Class F, but to operate with a Class B rise. This ensures that you have plenty overload margin and the insulation should have a much extended life.


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[alehman]

For small gensets <2MW, it's common to insulate at class H (180C) and specify 105C rise. With the standard 40C ambient, this gives you a good margin of 180 - (105 + 40) = 35C. Some engineers specify large margins in hopes of obtaining better life or to better withstand the increased heating effects when high harmonic loads are being supplied.