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[TCML] Re: Transformer Calcs
Somewhere on the web I visited an electrical supply company that had a
calculator for ferrite core transformers but cannot find it. Mayby a google
search for that would turn it up as I didn't try that but in the meantime
you might find some alternatives here ...
http://home.earthlink.net/~jimlux/hv/hvmain.htm Best Regards, Jerry
On Sun, May 3, 2009 at 1:00 PM, <tesla-request@xxxxxxxxxx> wrote:
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> Today's Topics:
>
> 1. Ballasting my Homemade Transformer. (Phil Tuck)
> 2. Re: Ballasting my Homemade Transformer. (David Dean)
> 3. Re: Ballasting my Homemade Transformer. (BunnyKiller)
> 4. Re: Ballasting my Homemade Transformer (Phil Tuck)
> 5. RE: Ballasting my Homemade Transformer. (david baehr)
> 6. Re: Ballasting my Homemade Transformer. (David Rieben)
>
>
> ---------- Forwarded message ----------
> From: "Phil Tuck" <follies@xxxxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Date: Sat, 2 May 2009 21:32:49 +0100
> Subject: [TCML] Ballasting my Homemade Transformer.
> 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
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: David Dean <deano@xxxxxxxxxxxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Date: Sat, 2 May 2009 21:42:12 -0500
> Subject: Re: [TCML] Ballasting my Homemade Transformer.
> Hi
>
> On Saturday 02 May 2009 03:32:49 pm Phil Tuck wrote:
> > 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?
> >
> With a perfect theoretical ballast and a a perfect theoretical transformer,
> when
> the transformer's secondary is open all the input voltage is dropped across
> the
> transformer primary, and none across the ballast. With the transformer's
> secondary shorted, all the voltage drop is across the ballast and none
> across
> the transformer.
> >
> > 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.
> If you find one, let me know.
>
> later
> deano
>
>
>
>
> ---------- Forwarded message ----------
> From: BunnyKiller <bunnikillr@xxxxxxx>
> To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
> Date: Sat, 02 May 2009 22:15:04 -0500
> Subject: Re: [TCML] Ballasting my Homemade Transformer.
> Hey Phil...
>
> 2 main concerns when making your own inductive ballast are wire size to be
> used and the number of turns required to have about 1-2 volts per turn...
> ok well there are 3 things to think about.. core size!
>
> First off, how much current do you plan to pump thru the ballast? A #10
> THHN solid copper wire is good for 25A at 180 turns on a core of about 12
> sqr inches.
> more amps needed?? go to a thicker wire ( # 8 or 6) keep turns in the 180
> -210 value, and increase the core area to 16 - 18 sqr inches....
>
> 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.
>
> Best bet, use wire to meet the maximum amount of current you need to
> supply the trannie with, keep the volts per turn to about 1 - 1.5 and keep
> the sqr inches of core to handle 3 amps per sqr inch, this should set you in
> a good direction and you will have a happy inductor....
>
>
> 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
>>
>>
>>
>>
>>
>>
>>
>>
>>
>>
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>>
>>
>>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: "Phil Tuck" <follies@xxxxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Date: Sun, 3 May 2009 08:41:35 +0100
> Subject: Re: [TCML] Ballasting my Homemade Transformer
> Thanks for both of those replies, I wanted to check my own understanding
> was
> correct before I went down the wrong 'garden path' with my thinking. I had
> read Richie Burnett's page
> http://www.richieburnett.co.uk/ballast.html#inductive in which he
> mentions
> the short is reflected back to the primary resulting in all the volts are
> dropped across the inductor, but other old archive postings also told of
> overheating ballast coils.
>
> This to my 55 year old DC 'trained' mind equated to a DC resistor. But of
> course I^2 * R, at the currents we are using, soon becomes several hundred
> watts just on the coils *own*winding resistance - this was where I had been
> confused.
>
> (Another handy page was this one
> http://myweb.tiscali.co.uk/teslatutorial/ballast.htm )
>
> Provided I use a big enough conductor size to keep its R value down, and
> enough turns for the required inductance on a suitable core (thermal and
> saturation issues) I will be ok.
>
> I have the option of getting an old 35 Kg three phase inductor, or using a
> couple of the four pairs of 'C' sections that are 2 sq inches each, so
> either way my modest 16 amps is easily attainable.
>
>
>
> Thanks for your input and help.
>
>
>
> Regards
>
>
>
> Phil
>
> www.follytowers.co.uk/tesla
>
>
>
>
>
>
>
>
>
>
>
>
>
>
> ---------- Forwarded message ----------
> From: david baehr <dfb25@xxxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Date: Sun, 3 May 2009 13:00:40 +0000
> Subject: RE: [TCML] Ballasting my Homemade Transformer.
>
> 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
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >
> > >_______________________________________________
> > >Tesla mailing list
> > >Tesla@xxxxxxxxxxxxxx
> > >http://www.pupman.com/mailman/listinfo/tesla
> > >
> > >
> > >
> >
> >
> > _______________________________________________
> > Tesla mailing list
> > Tesla@xxxxxxxxxxxxxx
> > http://www.pupman.com/mailman/listinfo/tesla
>
> _________________________________________________________________
> Hotmail® has a new way to see what's up with your friends.
>
> http://windowslive.com/Tutorial/Hotmail/WhatsNew?ocid=TXT_TAGLM_WL_HM_Tutorial_WhatsNew1_052009
>
>
> ---------- Forwarded message ----------
> From: "David Rieben" <drieben@xxxxxxxxxxx>
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Sun, 3 May 2009 08:37:27 -0500
> Subject: Re: [TCML] Ballasting my Homemade Transformer.
> Hi all,
>
> I took the core of a gutted defunct x-ray transformer (I
> seem to burn them out a lot ;^(), and rewound each
> "leg" with 105 turns of #8 THNN building wire, in pa-
> rallel. Since #8 is rated for 40 amps continuous current
> flow, I should be good for 80 amps continuous, at least
> from the wire guage perspective. This core was not the
> alternately leaved "E" and "I" peice construction, but of
> the two solid "U"s, which rendered rewiring considerably
> easier. IIRC, each leg has about a 10 to 11 square inch
> cross section and each are wound with a ballast coil, so
> I'm assuming that the cross sectional area is additive ( >
> 20 sq. in. total). I simply experimented with a variaced 120
> volt source while adjusting the gap spacing between the "U"s
> to adjust for the desired current flow allowance. I found that
> 3/8" spacing allowed for enough flux leakage to allow about
> 95 to 100 amps to flow at 280 volts input to the ballast.
> I also employed forced air cooiling to the finished home-
> made ballast to assist in cooling. With this setup, I have
> to run it at near max current for several minutes non-stop
> before I am able to detect ANY warmth above ambient
> temperature by hand. Oh yea, I forgot to mention that I
> placed shim spacer sticks between each alternate layer
> of the coils to maintain well-formed coils and also to
> allow adequate ventiallation between the neighboring
> layers. You can see the two reddish colored coils of
> #8 THNN building wire of the ballast at the bottom of
> the control panle in this "Green Monster Control Panel"
> photo:
> http://www.flickr.com/photos/33464569@N05/3118524350/
>
> David
>
>
> ----- Original Message ----- From: "david baehr" <dfb25@xxxxxxxxxxx>
> To: <tesla@xxxxxxxxxx>
> Sent: Sunday, May 03, 2009 8:00 AM
> Subject: RE: [TCML] Ballasting my Homemade Transformer.
>
>
>
> 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
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >
>> >_______________________________________________
>> >Tesla mailing list
>> >Tesla@xxxxxxxxxxxxxx
>> >http://www.pupman.com/mailman/listinfo/tesla
>> >
>> >
>> >
>>
>>
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxx
>> http://www.pupman.com/mailman/listinfo/tesla
>>
>
> _________________________________________________________________
> Hotmail® has a new way to see what's up with your friends.
>
> http://windowslive.com/Tutorial/Hotmail/WhatsNew?ocid=TXT_TAGLM_WL_HM_Tutorial_WhatsNew1_052009_______________________________________________
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>
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> Tesla mailing list
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>
>
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