-----Original Message-----
From: Ian White, G3SEK <G3SEK@ifwtech.com>
To: amps@contesting.com <amps@contesting.com>
To: <amps@contesting.com>
Date: 08 October 2001 13:00
Subject: Re: [AMPS] Discharge energy
>
>Steve Thompson wrote:
>>
>>From Phil, K5PC:
>>>The value of the glitch resistor is
>>>selected to limit energy discharge from the filter caps to 50 joules,
>>>and the wattage of the glitch resistor is selected to keep it from
>>>self-destructing while the breaker is in transit.
>>
>>First of all, please can I stress that my comments are NOT intended as
>>specific to Phil - his posting contains a comment I've seen a number of
>>times, which might appear in some manufacturer's info and which puzzles me
a
>>bit. Phil's posting gets used purely because I've chosen this moment to
make
>>my comment.
>>
>>The energy in the filter caps is defined as 1/2*C*V^2. I'm puzzled as to
how
>>a glitch resistor allows the *energy* in a discharge to be controlled. To
my
>>mind, it can only set the peak current and the time constant.
>>
>
>When the capacitor is discharged through the series combination of the
>resistor and the tube, the stored energy is divided between those two
>components. Strictly speaking the energy going into the tube is not
>limited, but shared.
>
>If there is an arc, the voltage across the tube drops to only a few tens
>of volts, so almost all the energy from a HV supply goes into the series
>resistor. In that sense the resistor limits the energy available to go
>into the tube.
The fog clears. Thanks, Ian
Steve
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