# How does a reactive ballast work?

I want to use a MOT (microwave oven transformer) for something it's not intended for. As a consequence, I need to limit the current so it doesn't melt itself. I am planning on connecting the ballast to the primary. The load on the secondary should be capacitive. I understand that a resistive ballast will limit current because V=I•R, so if V is constant, I will be relatively constant.

How does a reactive ballast limit current? Can I use a capacitor instead of the usual inductor? If I use both (in series) to correct the power factor, will that counteract the ballasting? Will connecting two MOTs, primaries in parallel, secondaries in series, change much?

• Would this unintended use happen to involve big sparks? Because, that would be awesome. – Phil Frost Dec 19 '13 at 19:57
• I'd like it to be part of a time machine or... maybe a tesla coil. – Andy aka Dec 19 '13 at 20:01
• IIRC people use magnetic shunts -- here is a good website: wiki.4hv.org/index.php/Microwave_oven_transformer Alternatively can't you use a second MOT as an inductor ballast? – HL-SDK Dec 19 '13 at 20:14
• I'd like it to be for a Tesla Coil, though from reading that article (@HL-SDK), that wouldn't be a good idea. I also have more capacitors than inductors. – Ethan Reesor Mar 18 '14 at 4:16