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# High voltage transformer current limiting?

I have modified a MOT to output 10kV as a Tesla coil power supply but when testing I found that there was a very low voltage (maybe 2kV).

The primary resistance was measured at 0.2ohm much less than the inductive ballast I've used to current limit. Is the voltage being drawn away from the primary to the ballast?

If so how can I resolve this (keep in mind even with the ballast it still needs further current limiting)?

## Discussions

7 years ago

What is this current limit you are using ?

Do you realize when you limit current you imply reduction in voltage.

I gather you want to reach 10KV ( how are you measuring your KVs ?)

what makes you decide you need current limiting ? and where ?

What is your limiting device ?

Is the transformer like the PLL SSTC of questions ago ?

A circuit would be of some help.

A

Answer 7 years ago

The MOT is current limited in series on the primary side with an inductor.

I do realise if I current limit I will imply reduction in voltage and I think that may be the problem.

I am measuring my kVs by the millimetre 1.1kV for 1mm.

Even with the inductor it still blows the fuses.

This one isn't for the PLL SSTC.

Answer 7 years ago

So what value fuses are you evaporating the metal from ?

You are using an inductor of unknown inductance, to me, to limit current.

That implies you are using AC power. You mention Tesla coil power supply.

And that means you could try resonating with the primary

which should increase the voltage substantially at no extra current.

I am limited to guessing on the skimpy information you provide no circuit

( It is your historical way of asking :-)

But I can tell you are not resonating with your primary.

Perhaps you should replace the inductor with a high voltage AC capacitor to

limit your current and when you hit the correct reactance it may resonate for you.

A

Answer 7 years ago

10A fuses (keep in mind the 240V not 120V).

I can estimate the inductance of the inductor to be 10-20H.

Sorry that I've been unspecific I might try that capacitor idea.

Thanks.

Answer 7 years ago

Start high VAC as you can 400VAC and start low capacity 1uF, 2, 5,10,35,80,120

A

Answer 7 years ago

Place the capacitor in series right?

Answer 7 years ago

Correct.