Re: Discharging HV Caps

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

Original poster: "William Graves by way of Terry Fritz <twftesla-at-qwest-dot-net>" <graves-at-jps-dot-net>

Please allow me to expand my earlier remarks.  To discharge a capacitor,
you follow the normal
safety procedure first.  Generally, there is a high-voltage resistor or
chain thereof
permanently attached to short the electrodes of each capacitor rendering it
safe after a time
elapses of, say, 10RC which gives a 99.99% discharge.  The problem is that
this little jewel of
a bleeder resistor can fail in place and you won't know about it until you
stick you hand in
there.  You can measure the voltage with a meter and a high-voltage probe
to shunt the voltage,
but you can still make a mistake either in setting the meter or in having a
failed probe you
don't know about.  So after you think you have discharged the cap and
measured the voltage if
you happen to have the equipment, before you put your hand in there, lay a
continuous piece of
metal across the electrodes.  It is better to lose a cap, a screwdriver, or
whatever than you
life.  The proper way to do this is from a distance with a shorting bar
(crowbar) on a long
insulated handle while wearing safety glasses.  But always do it.  This
practice has saved my
life.

Tesla list wrote:

> Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<jimlux-at-earthlink-dot-net>
>
> Depending on the value and voltage, discharging through a suitable resistor
> to dump the energy in a "non-explosive" way.  That is, shorting that 5 kJ
> energy storage cap with a big screwdriver is asking for trouble.  I use a
> big 300 ohm 300 Watt resistor.
> ----- Original Message -----
> From: "Tesla list" <tesla-at-pupman-dot-com>
> To: <tesla-at-pupman-dot-com>
> Sent: Tuesday, June 05, 2001 10:29 AM
> Subject: Discharging HV Caps
>
> > Original poster: "Ben Murrell by way of Terry Fritz <twftesla-at-qwest-dot-net>"
> <benmurrell-at-att-dot-net>
> >
> > WHat is a convenient way to dischage HV caps that is still safe?
> > Ben
> >
> >
> >