I rewired a microwave oven transformer to have an output of 40V and a center tab. With no load the primary gets hot really fast. I measured the current draw with no load and it pulls about 10 amps. So if my math is correct that is 1.2 kilowatts and that is way too much.
I need an output of 40 volts 10 amps that is 400 watts. If I am correct you can limit the current to the primary winding using an oil filled capacitor. So with some leyway, if I current limit the transformer to only pull 450 watts it should run much cooler.
What value capacitor to use? Is there a formula?