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Re: PFC caps - recommended type?

Original poster: "by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Tesla729-at-cs-dot-com>

In a message dated 5/13/01 11:44:07 PM Central Daylight Time, 
tesla-at-pupman-dot-com writes: 

> Can anyone tell me if these might work? 
> http://users.cnmnetwork-dot-com/~doemalibu/capmallory.jpg 
> They're Mallory caps, marked 100 MFD 250 VDC  (am I correct in assuming 
> MFD means uF, i.e. microfarads?) 
>    Thanks, 
>    Bill Vanyo 

Hi Bill, 

I'm afraid those caps are the polarized electrolytic type 
and are NOT suitable for AC PFC use, as they would 
quickly turn into a smoke bomb if hooked to AC. 

You want the oval-shaped oil-filled metal can types of 
capacitors, like the ones in the back of an A/C unit. 
They are always rated by volts AC, not DC. Also, make 
sure that they are "motor run" caps and not "motor start" 
caps. The motor start caps are usually a black plastic 
cylinder and are rated at X uFD to X uFD (example 188 
to 235 uFD). A motor run cap is alway rated at only one 
capacitance ( 5, 10, 25 uFD, ect). The motor start caps 
will also quickly overheat if connected to a constant AC 

Hope this helps you out. 

David Rieben