Newsgroups: sci.physics,sci.physics.plasma

Date: 10 Jun 2005 04:40:02 -0000

Organization: Thrasher Anonymous Remailer

Message-ID: <L3OACUWP38513.5278009259@reece.net.au>

From: Dave Sullivan <no@spam.com>

Subject: Re: 2 kW arc

References: <Z9GF0TAK38512.5127430556@reece.net.au>

<76lga1hbtl7o6ofe4c018st9j6qun055e0@4ax.com>

John C. Polasek wrote:

> A few comments. First your transformer with 240V 240 turns m/l is

> running at 1 volt/turn which is where iron will almost saturate

> at 60 cycles.

50 Hz. That is worse, right?

> It may be you are trying to get too much out of the iron which is

> at its limit.

I'm not sure, what the problem is here. I'll take whatever

the secondary gives. May that cause more than linear heat

production in the primary or the core? Or is just the output

limited?

> Secondly, if you notice welders using welding rods about 1/8".

> Your carbons are too large.

Yeah, I picked large carbons, but how is that a problem?

> Third, watts is watts; use a resistor instead. There's no merit

> in making 5000 degrees at the teeny weeny arc.

Good point. But an arc won't melt down. I'm building an oven with

CrNi wire which will be limited by the wire melting point. Also, I

want to use an arc because I love arcs.

> Arcing is difficult, HV to start and suddenly Low V.

If I push the rods until they touch and draw them apart I don't need

HV.

> Unless you have some special reason you'll do better with a

> resistor, which could be a cylinder of carbon. Do the arithmetic,

> bearing in mind breaker of 20A at 220V is your maximum. Sounds

> like 10ohms at straight 220V would give you max power.

That would need either a too long rod or one so thin it would break

or burn away too easily. But maybe I can experiment mixing graphite

with clay or magnesia.

> You never were specific about the rest of the oven.

I'm not sure about that. Since clay will fail at about the same

temperature as NiCr I'll try to make magnesia bricks in the

clay/NiCr oven.

> John Polasek

Thanks for your response. I searched the web again for some

hours and didn't find useful details about making arcs (with

graphit rods). Maybe the library might be worth a visit. I'm

crossposting to sci.physics.plasma now. Please check

sci.physics for the original post.

Dave