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#68404 - 08/07/06 01:20 PM Capacitor Voltage Rating and Life Expectancy  
wendel  Offline
Joined: Aug 2004
Posts: 55
On a 240 volt PSC motor, does it make economic sense to use a 440 volt run capacitor verses a 240 volt run capacitor? Does the higher voltage rating mean the capacitor's life might be extended?

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#68405 - 08/07/06 02:25 PM Re: Capacitor Voltage Rating and Life Expectancy  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,140
I always like a healthy cushion when I am using capacitors. I would go with the higher rated unit. Spikes and tolerance problems can overwealm a unit used at it's limit.

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#68406 - 08/07/06 02:31 PM Re: Capacitor Voltage Rating and Life Expectancy  
gfretwell  Offline

Joined: Jul 2004
Posts: 9,140
BTW "240v" is RMS. That capacitor sees peak to peak which is more like 336v and if the PoCo is peppy that day (like 250v RMS) it could be more like 350v p/p

Greg Fretwell

#68407 - 08/07/06 05:07 PM Re: Capacitor Voltage Rating and Life Expectancy  
WFO  Offline
Joined: Sep 2005
Posts: 202
Cat Spring, TX
I'm not sure, but I think a capacitor run at half its rated voltage gives you about 1/4 the effect in vars. I'm probably not saying this correctly so somebody feel free to correct me. But assuming all other aspects of the capacitors to be identical, it may not be adequate to do the job.

[This message has been edited by WFO (edited 08-07-2006).]

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