PFC voltage rating

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Jraef

Jraef

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She was right because the kVAR rating is different for 25HP at the different voltages?

Because there is no problem using a higher voltage rated capacitor, it’s only the kVAR rating that matters. Usually PFC caps are sold by kVAR, not HP because determining the kVAR that you need is often not that simple.
 
ptonsparky

ptonsparky

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Jraef said:
She was right because the kVAR rating is different for 25HP at the different voltages?

Because there is no problem using a higher voltage rated capacitor, it’s only the kVAR rating that matters. Usually PFC caps are sold by kVAR, not HP because determining the kVAR that you need is often not that simple.
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She was right because a 480v capacitor is considerably less kvar when operated at 240v.
Our suppliers only ask for the HP, and then give us a capacitor. I see the charts list different sizes depending on the frame and other details.
 
synchro

synchro

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The kVAR from a given capacitance value is proportional to the square of the applied voltage, and so the kVAR at 480V will be 4X the kVAR at 240V.
Therefore you'd need a 480V PFC unit with 4X the kVAR rating as one spec'd for 240V. But the 480V unit is going to cost more money because its capacitor can stand more voltage even though it has the same capacitance in μF as the 240V unit.
 
ptonsparky

ptonsparky

Tom
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synchro said:
The kVAR from a given capacitance value is proportional to the square of the applied voltage, and so the kVAR at 480V will be 4X the kVAR at 240V.
Therefore you'd need a 480V PFC unit with 4X the kVAR rating as one spec'd for 240V. But the 480V unit is going to cost more money because its capacitor can stand more voltage even though it has the same capacitance in μF as the 240V unit.
Click to expand...
Once I found the formula, that is just about what I figured out.

7-10 days delivery.
 
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mikeames

mikeames

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Someone remind me of what PVC stands for? I know its a starting CAP and I think its polyester????
 
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retirede

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mikeames said:
Someone remind me of what PVC stands for? I know its a starting CAP and I think its polyester????
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Polyester polypropelyne film capacitors are called PVC.
Maybe the guy who came up with the acronym was drunk? There’s probably a more reasonable explanation, but I’m too lazy to dig for it.
 
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