RE: [TCML] Ballasting my Homemade Transformer.

[david baehr <dfb25@xxxxxxxxxxx>]

Hi,

    I also made a ballast a few years back, using a small book published by Lindsay called 'how to design and build a 200 amp welder' as a guide.  It states a rule of thumb of 2.25 -2.5 sq. in. of core for every 1000 watts,..also the 1.2 - 1.3 volts per turn ( 180- 200) seems to be a good rule(for 240v).  Im pushing my #12 wire a bit,...as i push 12-14 amps through it, but its low duty cycle :-)    its a neat LiL' book, but i think its out of print ??


 
> Date: Sat, 2 May 2009 22:15:04 -0500
> From: bunnikillr@xxxxxxx
> To: tesla@xxxxxxxxxx
> Subject: Re: [TCML] Ballasting my Homemade Transformer.
> CC: 
> 
> Hey Phil...
> 
> Im running a ballast with 3 #10 THHN solid copper in paralell on a 25 
> sqr inch core at 200 turns... The "I" section is adjustable via PE 
> "shims" ( used to be wood) for current control from 5 amps at 280VAC to 
> 100 amps ( depending on where I set the I section of the core at, 
> presently its set at 60 amps max). Granted, its a big core assembly, 
> but it doesnt suffer from heating issues even at 60 amps at 5+ minutes 
> run time....
> 
> seems that the core size along with input voltage ( approx 240V ) 
> roughly equates to about 4 amps per sqr inch before saturation becomes 
> an issue... but thats just my experiences I have noted.
> 
> As far as voltage drop, my unit has about 5 - 10 volts difference 
> before and after the inductor between an input of 120 -280 vac.
> 
> > 
> Scot D
> 
> 
> 
> Phil Tuck wrote:
> 
> >Hello.
> >
> >I have finally got my homemade transformer running and now face the
> >delightful task of ballasting it. Its output, based on scaling up low
> >voltage readings, will be 10 to 11K (3.7kva approx) limited by the number
> >of turns and the window winding size unfortunately. Primary will be set up
> >for 16 amps with around 375 m/a secondary (235v / 240v system). (Primary =
> >Bifilar AWG 14, Secondary = AWG 27)
> >
> > 
> >
> > 
> >
> >Two quick questions:
> >
> >Question 1:
> >
> >As a perfect theoretical ballast will have no resistance, is it true to say
> >that when using an inductive ballast for my transformer, the only voltage
> >drop across the ballast will be caused by the ballast's resistive component
> >? 
> >
> >In other words if I wind an inductive ballast coil of the correct mH rating
> >(using chunky wire on a 4 square inch core so it has low ohm resistance) I
> >should get almost full voltage going into the tranny, with little voltage
> >drop across the inductive ballast?
> >
> > 
> >
> >Question 2:
> >
> >There are various inductance calculators around, but they are all for
> >air-cored as far as I can see. Anyone know a link to one that caters for a
> >laminated core. It will still be a bit of a guess as I don't know the cores
> >magnetic specifications, but it will be better than using an air cored
> >example. I am trying to avoid the hit and miss method of wind / measure /
> >wind / measure etc, as I will be winding onto a bobbin using a lathe.
> >
> > 
> >
> > 
> >
> >Regards
> >
> > 
> >
> >Phil
> >
> >www.follytowers.co.uk/tesla
> >
> > 
> >
> > 
> >
> > 
> >
> > 
> >
> > 
> >
> >_______________________________________________
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> >
> > 
> >
> 
> 
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