# Current Limiting

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From:  baumann-at-proton.llumc.edu [SMTP:baumann-at-proton.llumc.edu]
Sent:  Thursday, January 29, 1998 2:16 AM
To:  tesla-2-at-emachine-dot-com
Cc:  tesla-at-pupman-dot-com
Subject:  Current Limiting

I was thinking this morning about current limiting.. [I still dream of
the day I can get that Pig... and want to be ready] I thought of
something that is a) very simple, and b) probably does not work.
So someone tell me why please :)
Since I am mostly a software kinda guy, with a smattering of digital
design, dealing with this high-power AC stuff always confuses me.

If I understand it correctly - the idea behind reactive or resistive
loads is to place an IR drop in series with the pig, such that when
the current reaches a certain point, the IR loss prevents it from
rising further [I know, the wording sucks, but the idea is
clear, I hope]
So.. based on this idea.. and the fact that lightbulbs don't exactly
short things out, why not use lightbulbs as resistive ballast?
I am not exactly sure what the VA rating for a bulb is.. but for
grins sake, assume a 100W bulb is 100VA, paralleling 2 bulbs gives
you total power flow of 200VA, 3.. etc. [ for 220, use 2 110V bulbs in
series].

Power control is two fold: Voltage via variac, and current by switching
in more or less bulbs in series.

Like So  (god I hate ascii art)

HOT--------------------------------------------
|         |          |         |       |
B	  B          B         B       B       B=lightbulb
|         |          |         |       |       S= Switch
VARIAC  S         S          S         S       S
|         |          |         |       |
----------------------------------------------
Pig
NEU---------------------------------------------------

So. it's stupidly simple. Despite the engineering approach of KISS,
there must be someting wrong - else it would be used. So someone please
exlain where my logic went off the deep end.

--
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Michael Baumann  Optivus Technology Inc.|Loma Linda University Medical Center
San Bernardino, California. (909)799-8308 |Internet: baumann-at-llumc.edu

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