[Amps] Help on Aerovox capacitor

[Will Matney]

Ken, Mike, and Dennis,

Unless the catalog states that the capacitor is a non-polarized type, it 
will be polarized and need to be connected correctly, positive to 
positive, etc. The case being connected to one plate (cathode) can not 
tell if it is or not. The positive plate (anode) has been etched and has 
a coating formed on its surface in a polarized capacitor. The cathode 
plate does not have this and is merely used as a connection for the 
current flow where the electrolyte actually acts as the cathode. The 
electrolyte contacting the coating on the anode forms the capacitor in a 
polarized electrolytic forming somewhat a circuit like a diode. A 
non-polarized capacitor is not made this way and acts different. If a 
reverse current is placed on the plates, the coating can be destroyed 
quickly and at a pretty low reverse voltage too. The capacitor will heat 
up and eventually blow. I would imagine that if one terminal has a 
circle at it and the other does not, it is polarized. Again, if the 
catalog does not state the capacitor is a non-polarized one, then treat 
it as a polarized type. Hope this helps.

Will Matney




kenw2dtc wrote:

> I agree with Dennis on his assessment of the cap with this added 
> thought. Since the internals are wound like a roll of paper towels in 
> oil, it is possible that the outside layer is closer to the physical 
> case and thus have a lower breakdown voltage to the case than the 
> inside layer terminal?  Thus if the cap is insulated from the chassis, 
> no polarity should be noted, but if the cap is mounted on a chassis 
> with other wiring, the red dot should be the positive terminal?
> Just asking.....
>
> 73,
> Ken W2DTC
>
> ----- Original Message ----- From: "Mike Clarson" <mclarson at rcc.com>
> To: "'Dennis Berry'" <dennisberry at worldnet.att.net>; 
> <amps at contesting.com>
> Sent: Thursday, December 16, 2004 11:05 AM
> Subject: RE: [Amps] Help on Aerovox capacitor
>
>
>> Dennis: My data shows this cap as an "immersion-proof" unit. Intended 
>> for
>> continuous heavy duty use. Used HYVOL (the oil?) that allows compact 
>> size
>> with high capacity. Looks like an oil filled unit, and polarity 
>> should not
>> matter. Neither side should be connected to case. I show dimensions 
>> of 4-5/8
>> x 3-3/4 x 3-3/16 (HxWxD) and it cost about $25 new.--Mike, WV2ZOW
>>
>> -----Original Message-----
>> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com]On
>> Behalf Of Dennis Berry
>> Sent: Thursday, December 16, 2004 12:06 AM
>> To: amps at contesting.com
>> Subject: [Amps] Help on Aerovox capacitor
>>
>>
>> I have an Aerovox No 9, A-10941-1, 8 MFD 2000vdc capacitor.  I have 
>> searched
>> on google, and the aerovox.com website for information on this cap.  My
>> guess is it is an older one since nothing is showing up with these part
>> numbers.
>>
>> Does anyone have info on this cap (other than mfd and voltage, that 
>> is the
>> obvious part).  In particular, how did Aerovox mark their positive or
>> negative terminal?  The cap has a round dot in the can at one end, 
>> but there
>> is no paint on it to indicate if it was a positive or negative.  Did 
>> Aerovox
>> uses a standard marking for their part?  I am assuming this would be a
>> polarized capacitor with that MFD and voltage rating.
>>
>> Anyone with an older catalog that can help me out with additional info?
>>
>> Thanks,
>>
>>    Dennis
>> _
>>
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>
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