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Re: trigger
> Date: Wed, 22 Jan 1997 22:25:23 -0700
> From: Tesla List <tesla-at-poodle.pupman-dot-com>
> To: Tesla-list-subscribers-at-poodle.pupman-dot-com
> Subject: Re: trigger
> Reply-to: tesla-at-pupman-dot-com
> Subscriber: Benson_Barry%PAX5-at-mr.nawcad.navy.mil Wed Jan 22 21:50:42 1997
> Date: Wed, 22 Jan 1997 12:40:00 -0500 (EST)
> From: Benson_Barry%PAX5-at-mr.nawcad.navy.mil
> To: tesla-at-poodle.pupman-dot-com
> Subject: Re: trigger
>
>
> Hi Dave, all,
> The current rating of a capacitor for pulse discharge service
> is usually specified in the manufacturers data sheet or
> catalog as a ratio of the number of shots to current
> above design value. Too much current such as from
> a direct short across the terminals of the capacitor
> can cause several undesirable effects such as:
> 1. Dielectric dissipation can become so great that
> the dielectric heats up and ruptures. The oil
> then vaporizes and forms a gas that forces
> the can or porcelain insulator apart explosively.
> 2. The foil that comprises the plates of the capacitor
> can melt, open up, and arc internally. This will
> have the same affect as above.
> 3. The internal connections can melt, break, and
> arc with the above result.
> 4. The electroacoustic shock wave from the
> capacitor discharging can cause things such as
> connection leads and foil to break. It can also
> overcompress the dielectric causing it to abrade,
> wrinkle, and rupture. The ringing waveform
> multiplies this stress N times.
> If your capacitors are for high voltage filtration
> then their lifetime will be limited by how much
> the discharge current exceeds the design ripple
> current. And then there are manufacturing
> defects the effect of which everyone on
> this list is well aware from the CP incident!
> You can seldom tell when a capacitor
> whishes to die catastrophically but if it is
> well shielded then it can't take you with
> it!
> Barry
>
>
> ----------
> From: "tesla"-at-poodle.pupman-dot-com-at-PMDF-at-PAXMB1
> To: Benson Barry; "Tesla-list-subscribers"-at-poodle.pupman-dot-com-at-PMDF-at-PAXMB1
> Subject: Re: trigger
> Date: Saturday, January 18, 1997 3:19AM
>
> <<File Attachment: 00000000.TXT>>
> Subscriber: dbell-at-baygate.bayarea-dot-net Fri Jan 17 22:38:33 1997
> Date: Fri, 17 Jan 1997 07:21:23 -0800 (PST)
> From: Dave Bell <dbell-at-baygate.bayarea-dot-net>
> To: Tesla List <tesla-at-poodle.pupman-dot-com>
> Subject: Re: trigger
>
> Barry:
>
> Thanks for putting your "off-topic" post up on the
> Tesla coil list. This capacitor discharge topic is one
> I've been wanting to work on for a long time. I appreciate
> your safety notes and circuit suggestions!
>
> What exactly did you mean by the following?
>
> > Your load should not exceed the current rating of the capacitors.
>
> What *is* the current rating of a capacitor??
>
> I have available a set of eight caps from a high voltage
> pulse forming network, that I've been dying (no pun intended!!)
> to put into this application. They are each rated at 248 uF/5 kV.
> That's a LOT of energy...
>
> Dave
Barry,
Outstanding insight and explanation on the potential hazards and
mechanisms of failure explained for big single bang mode use of
capacitors!. Thank's from many of us I'm sure.
rwstephens