Re: HV Cap testing,

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "BunnyKiller by way of Terry Fritz <twftesla-at-qwest-dot-net>" <bigfoo39-at-telocity-dot-com>

Tesla list wrote:

> Original poster: "Jonathan Peakall by way of Terry Fritz
<twftesla-at-qwest-dot-net>" <jpeakall-at-mcn-dot-org>
>
> Howdy,
>
> Can someone point me to a good source of info regarding testing caps
> with voltage? I tried putting 120vac into my caps, then testing them
> with a DMM, and all I get is a brief reading that is much lower than
> 120v. What is the proper way to do this,
>
> Thaks all,
>
> Jonathan

Hi Jonathan...

all depends on what type of cap you are testing...  A/C or D/C ... if you
are testing for voltage
retention or if you are trying to test for "capacitance"  also if the cap
has a built in bleeder
resistor, this will affect your readings too.  for a "capacitance" reading
, you will need a meter
that reads capacitance. ( radio shack has a decient Multi Meter that is
capable )

for a DC cap no bleeder resistor ---  a dc voltage applied to the cap for
about several minutes
should reach the DC voltage supply ratings. e.g. a 200V DC cap will take a
12V DC charge and retain
it for a few minutes, long enuf to read 12V for a couple of seconds (
depending upon the meter you
are using to read the voltage... not all meters use the same resistance )

AC caps supplied with an AC voltage supply will give you various readings
due to the point of when
you remove the AC supply...  if done at the right moment you could get a 0
V reading....  it is safe
to "charge" a AC cap with DC to see if it holding a voltage.

If you are trying to see if a hi volt cap is holding a hi volt charge...
then you will need a hi
volt DC supply ( rectified (( full wave)) AC supply) and a volt meter
designed for hi volt
application, unless you have access to a 50KV 1 meg resistor and a regular
volt meter) you can then
test the cap to see if it is holding a hi volt charge  ( but you will need
to know the "full swing"
scale amperage of the MM to adjust the readings).

soo  I guess it really isnt all that simple....

let us know a bit more about what type of cap and exactly what reading you
want...


Scot D