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Three phase induction motors

  • Thread starter Aaron321
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  • #1
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hey does anyone know the effiency and power factor of a typical three phase induction motor?

cheers,
 
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Answers and Replies

  • #2
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Well, it's always a good thing to start off with the definitions of efficiency, power, and power factor.

Let [tex]\eta[/tex] be the efficiency, then [tex]\eta = \frac{P_{out}}{P_{in}}[/tex]
Let P= power, then P=VI.

Therefore the average Power = [tex]VIcos(\theta) [/tex]
By definition of power factor, it is the ratio of average power/VI.
Thus, the definition of power factor = [tex]\frac{VIcos(\theta)}{VI}=cos(\theta)[/tex]

From here, use the Pythagorean theorem to solve for power factor of a three phase
 

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