RE: [TCML] Taming the Beast: Inductive Ballast vs. Variac, PFC

[david baehr <dfb25@xxxxxxxxxxx>]

Ive made such a ballast (although, not as nice lookin' ),.....I built up an 'E' core & 'I' core from an OL' trans from a salvage yard.
 
      made a cardboard & fiberglas resin bobbin for the windings,......when I went to buy the large magnet wire from a tranformer shop,..the owner was very helpfull, & sat down with me to discuss my requirements,....brought up a program on his PC for turns,wire size , etc, etc.........I shim my 'I'  with LDP  ,........I went with #12  for my 3kva ,.....but my winding window is quite large,......I should have gone with a little larger wire,..but works great with my 'small' system.....it didnt cost to many $$$.....
 
> Date: Mon, 26 May 2008 11:46:42 -0700> From: bartb@xxxxxxxxxxxxxxxx> To: tesla@xxxxxxxxxx> Subject: Re: [TCML] Taming the Beast: Inductive Ballast vs. Variac, PFC> CC: > > Hi Jeremy,> > There are welders, variacs, and homemade pipe ballasts used for > inductive current limiting in general. Some have also used MOT's or > other iron core transformers. I use a variac. I would like to change > over to an air gap ballast some day based on what Richie Burnett has > done. It's just something to consider if you happen upon a nice core > someday. May even spark other ideas.> > Mechanically, it's a ballast with with the turns wrapped around the > center core. The top of the core is adjustable and this is where Richie > sets the air gap for current control. He used high density polystyrene > to fill the gap preventing the magnetic field from collapsing the air > gap. This is probably the best ballast idea I've seen. Anyway, you can > see pics and read about it here. In my opinion, this is really an ideal > ballast as it can be set for any TC transformer current (small to > large), it's compact, and it's efficient.> http://www.richieburnett.co.uk/parts2.html#ballast> > Richie was going to put together a program way back when for inductive > ballast design, but I don't think that actually transpired. Regardless, > Richie does have a procedure in the TCML archives which helps shed light > on this subject.> http://www.pupman.com/listarchives/2001/June/msg00744.html> > Richie Burnett's web pages in my opinion are the most informative on the > internet.> http://www.richieburnett.co.uk/tesla.shtml> > Take care,> Bart> > > Jeremy Scott wrote:> > Hello Coilers!> >> > I'm getting back into the 'hobby' after a few years of> > being out. A little rusty on my theory and math. I've> > accumulated some stuff since then and would like to> > build another coil using some parts from my old coils.> >> >> > At the heart of my system is a 3KVA GE Potential> > Transformer. > >> > Most of the things I'm confused about is how to build> > the proper controls to tame this thing without blowing> > breakers. > >> > INDUCTIVE BALLAST:> >> > In the past I've used a 500 foot 12 gauge wire spool a> > la Home Depot. The problem with this is that the heat> > it generates almost melts the spool it's on. I think> > this is because there is no cooling for all but the> > outer layer of wire. > >> > I'd like to build a more robust and controllable> > ballast. > >> > My idea is to wrap the 500ft of wire around a PVC pipe> > of a diameter that is the average (half) of the> > spool's diameter and then slide a chunk of metal in> > and out of the pipe to control current. That half> > diameter thing is just a guess. I have no idea what> > the reactance > > of the spool is or how to recreate it in a more> > heat-dissipation user-friendly adjustable version> > using common parts.> >> > I'm also scared of turning my coil on full blast> > instantly. In the past I've used an expensive variac > > to dial the voltage up and look for problems, unwanted> > arcs etc, but I think it would be better to control> > the current instead. Perhaps both.> >> > I guess I'm looking for something that will limit up> > to 20A, so I can get all that the outlet will give> > without tripping a breaker. > >> > POWER FACTOR CORRECTION CAPS:> >> > Making the most of what I can get from the wall, I've> > got 6 oil filled 'can' capacitors wired in parallel> > across the primary. Each is 100uF @ 370VAC. I'm not> > sure if this is correct, I don't know the reactance of> > the transformer's primary to apply a formula. I did 6> > by trial and error, monitoring the current pulled from> > the outlet for the lowest value. It's probably> > completely wrong but it doesn't blow the breaker. :)> >> > Thanks in advance! -Jeremy> >> >> > > > _______________________________________________> > Tesla mailing list> > Tesla@xxxxxxxxxxxxxx> > http://www.pupman.com/mailman/listinfo/tesla> >> > > _______________________________________________> Tesla mailing list> Tesla@xxxxxxxxxxxxxx> http://www.pupman.com/mailman/listinfo/tesla
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