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RE: [TCML] pole pig question
Perhaps I missed something, but why is a 1 KOhm value being discussed? If it's to be used as a dummy load for a distribution transformer, such a low resistance value would, *if it could*, draw over 14 Amps. While I doubt that the high side of a distribution transformer could source 14 Amps, it is not a current limited transformer, and even if it managed to eek out more than 1 Amp, it would exceed the power rating of the 1kW resistor, and smoke it. Whether the smoke is due to over current or over voltage is difficult to predict and academic.
I guess more to the point, why is a dummy load for a distribution transformer even being considered? I would guess that it's rare that the transformer is faulty, and a lashed-up Jacobs's ladder should be adequate evidence of its functionality. A proper full-power dummy load resistor for a distribution transformer would be HUGE.
Regards, Gary Lau
> -----Original Message-----
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
> Behalf Of G Hunter
> Sent: Thursday, January 17, 2008 6:38 PM
> To: Tesla Coil Mailing List
> Subject: Re: [TCML] pole pig question
> --- BunnyKiller <bunnikillr@xxxxxxx> wrote:
> > Hey Jim,
> > test the piggie using a hi current hi voltage
> > resistor 1KW @ 1KOhm (
> > wire wound dont work to well they simply arc over to
> > the next winding)
> > Scot D
> I disagree. An ordinary wirewound power resistor is
> as good as any in this application. A 1kohm power
> resistor will feel no more than a few hundred volts
> potential across the whole body of the resistor, even
> if it is connected across the pig HV terminals. The
> reason is as simple as Ohm's law. If a 1kohm resistor
> passes 500mA of current, then it will have a potential
> of 500volts across it--hardly sufficient to cause
> turn-to-turn arcing on a big (100W or larger) one.
> The pig simply cannot develop it's full HV potential
> across such a low resistance. Besides, wirewounds
> have been used for decades in vacuum tube equipment,
> where they routinely handle 100's of volts of plate,
> grid, and screen bias without failure.
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