We have 3 identical 1.5mw Cat SR4 alternators. when hooked up to load bank at unity pf there is no problem with winding temperature, but at .8 pf at rated load the temperatures climb to 170c. Harmonics are fine

Grateful for any suggestions
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BT965... The alternator's nameplate will indicate rated-amperes, rated-kVA, and rated-PF. And, its rated-kW (or MW) will equal kVA x PF.

When connected to the load-bank, PF is 1.0 (often referred to as unity) thus the current-reading will be 0.8 x rated-amperes.

Stated another way, when loaded at rated-kVA and rated-PF, the current reading will be 1.25 x the current-reading when connected to the load-bank.

The higher current explains the higher winding-temperature!

This example illustrates how the torque-to-amp analogy is mis-leading!

Regards, Phil Corso

 

Heat dissipation =I^2* z right?

 

Namatimangan08... technically it is, dissipation = I^2*R!

Phil

 

>Namatimangan08... technically it is,
>dissipation = I^2*R!

You are right. Heat dissipation =I^2*R. It is not I^2*z. I should know this.

Thank you.