I assume that this transformer has E and I interlaced laminations. Since it sounds like you have a substantial amount of high-silicon iron here, you could do what I did and make a variable air gap ballast with this. I will warn you though that it is a lot of work to do correctly but well worth the effort. Start by removing the windings even though they are beautiful. I started with a 120/240/480 single phase transformer rated at 25 KVA which also had beautiful windings but away they went. Then delaminate the core so that you end up with 2 piles of laminations; one "E" and the other "I". I used a putty knife to get in between the laminations to pry them apart. Consult a transformer design book and determine how much iron and how many turns of wire you will need based on the maximum amount of current that you want to control. The next step is to make a bobbin for the coil. Insure that the bobbin will fit tightly over the center leg of the core's "E" section. Wind the coil on the bobbin and place this over the center leg of the "E" laminations. Keep the windings tight. The other 2 legs of the core will be used to close the magnetic flux loop. Make your "I" section of the core. Bolt everything together securely. The air gap is established with different thicknesses of G10 or any other hard insulator with precise thickness. Make sure that everything is tight or you will get an excessive amount of 60 Hz hum.
I made such a ballast for my pole pig and it works beautifully. It weighs about 75 pounds. My design can set the maximum current at anywhere from 4 amps to 40 amps at 240 volts with various air gap spacers. I used 8 gauge THHN wire for the coil, which is a real pain to wind tightly. The only heating the ballast experiences is at the interface between the E and I sections in a very small area where the magnetic flux lines leak out at the air gap. The core and wire remain cold. There are pictures posted of my ballast on the TCML "Photos" section under "Steve White".
----- Original Message -----
From: "jhowson4" <jhowson4@xxxxxxxxxxx>
To: "TCML tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Monday, February 12, 2018 8:37:02 PM
Subject: Re: [TCML] Three phase to Ballast?
Thanks Dave.
Quite the opposite actually, I was hoping to get 18ish or so volts at the higher current out of it. The windings are beautiful. Nice space wound 3 strands of hefty square magnet wire on the LV side. Can handle a bunch of current indefinitely. Or just use the inductance to ballast my pig. The core area is about right. Havnt bothered to throw an LCR on it yet.Anyway.
My uncertainty stems from the fact that the 3 phase cores have equal iron on all 3 legs, Such that if I only energized 1 coil the magnetic loops cross sectional area doubles and then halves again. Not sure if this would cause a negative effect making it an undesirable situation for a single coil single phase use.
I could always just cut out the middle leg... And use the two outer legs.
Someone on Facebook suggested putting all the secondaries and primaries in series with proper fields orientations. Maybe that works for lower power overall.
Regardless, Figured I'd ask the stupid questions before rigging up a test. The garage is coldish this time of year after all.
Cheers, Jay
Sent from my Verizon 4G LTE Smartphone
------ Original message------From: David Speck Date: Mon, Feb 12, 2018 8:52 PMTo: Tesla Coil Mailing List;Cc: Subject:Re: [TCML] Three phase to Ballast?
Jay,Aside from the three phase issue, I assume that you would be planning to feed 120 or 240 VAC into the 36 volt windings in an attempt to get a higher voltage (~2,300 VAC) out of the original 440 VAC terminals.I would not expect the transformer to last very long in this mode of operation, because the windings would not be insulated to handle such a high voltage. Furthermore, 2,300 volts is not a particularly high voltage to run a TC with. You can get nearly the same voltage out of an ordinary microwave oven transformer that was designed to handle such a voltage comfortably for extended periods.Two such MOTs connected together in series at their usually grounded cores would give you ~4,000 volts, but even that is rather low for TC use, unless you are going for a DC resonant charging system.DaveOn 2/12/2018 6:33 PM, jhowson4 wrote:> So, I have this huge 3 phase transformer that was slated to step down 480 to 36V at 600 or so amps.> My lack of 3 phase power has led me to wonder if I could use the transformer as a single phase input output via keeping/using only one set of the windings.> Has anyone used a 3 phase transformer as a single phase unit via isolating the unused coils and simply running just the middle leg?> Cheers, Jay_______________________________________________Tesla mailing listTesla@tedward.pupman.comhttps://www.pupman.com/mailman/listinfo/tesla
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