How can I build a heavy duty electrical transformer?

Question

I have built a magnetic type of generator producing 20000+ volts but only around 4-5 amps continuous DC power, problem is,no one manufactures a step down transformer to knock down voltage and increase amperage . apparently I need to build this as well. If I can knock it down to a managable voltage/amperage I can find a transformer that will suit my needs. Size is an issue it needs to compact enough to fit in an engine bay with all my other electrical gadgets. This for an EV by the way. Any formulas for wire gauge, turns ratio, and types of materials for the core would be greatly appreciated, THANKS

Answer 1

You have asked this before. Same answer applies.

Transformers do not work on DC. Never, ever.

It takes a lot of large and expensive electronics to convert 20kV DC to something manageable. The power companies do this for DC transmission lines.

Answer 2

If you refuse to understand that you simply cannot "transform"

"continuous DC power" , I for-see a Darwin Award in your

immediate future if you continue to mess about with 20 KV.

Even if it were possible, a 90 KVA magnetic transformer would

fill the average 'engine bay'.

Answer 3

If you don't need the 20 KV, why are you generating at that voltage? Generate the voltage that you will actually use. Much easier to deal with lower voltages.

As the previous person wrote, there is no way to use a transformer for DC. Either generate AC and transform or generate DC at the voltage that you need.

Also, 80-100 KW is a lot of power. No matter what you build, it's going to be big

Answer 4

As others have said, there are some discrepancies in your question, 100kW is a lot of power (about 130Hp) , what are you driving your generator with? perhaps you meant 4-5 milliamps? if so, except for the DC problem (which is a big problem), that would be in neon sign transformer territory (used "backwards" as a step down),

Your biggest problem is not the magnetic design, it's switching your DC to create an alternating field for the transformers, since as Bill said, transformers don't work on DC, and 20kV switching is not all that easy to do.

[EDIT]

Some people seem to be giving you a hard time about not understanding that transformers don't work with DC, perhaps they haven't read the "additional information" where you mention the "perendev mag motor".

Had they read that they would realize transformers are the least of your problems.

I suggest you get your perendev mag motor to the point where it will run for 30 minutes with no load (_and_ the starting battery _disconnected_) before you bother worrying about the transformer, since that will never happen, you will not need to worry about a transformer.

Answer 5

OK, let's say that you could convert the 20kV to AC so you could use a transformer.

Listen carefully:

You CANNOT build a transformer for 20kV on your own.  I have worked with these type of transformers, and I really, really know what I am talking about.  More than turns ratio and core materials, it is mainly about maintaining insulation integrity throughout.

There are companies that build transformers like the one you need - but they ain't cheap.  These are the type of transformers that a company involved in electric-traction could easily produce - an ABB or Siemens.  But nothing good can come from you trying it on your own.

Answer 6

Well, you have your work cut out, that's for sure. The problem I see is that your voltage waveform from the auto coils is going to be anything BUT sinusoidal. This makes the design of the transformer both difficult and EXPENSIVE. It would be much cheaper to start again from scratch and design and build another generator.