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@rcc.com>
To: "'Dennis Berry'" <dennisberry@worldnet.att.net>;
<amps@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@contesting.com [mailto:amps-bounces@contesting.com]On
Behalf Of Dennis Berry
Sent: Thursday, December 16, 2004 12:06 AM
To: amps@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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