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Re: Current Limiting and Impedence



Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

Hi Steve,

These are tough issues for someone that hasn't dealt with ballast inductors before. I thank you for all your supportive explainations.

Gerry R


Original poster: Steve Conner <steve@xxxxxxxxxxxx>

At 00:09 08/05/05 -0600, you wrote:
Original poster: "Gerald  Reynolds" <gerryreynolds@xxxxxxxxxxxxx>

I'll reply to my own reply.

Maybe what I'm missing is: if I increase the area to prevent saturation, the inductance goes back up so maybe this is self defeating.

Yes. That's exactly what the issue is. If you design a gapless ballast so it won't saturate, then the inductance will be too high to let any decent current flow. If you design it with low enough inductance to pass your desired current, it will saturate too early.


If you want a practical demonstration, try ballasting a fluorescent lamp with a transformer primary instead of the proper ballast. No matter what you do, you can't find a tapping point that makes it work, it goes straight from a dim flickering light to saturating and burning the lamp out. Well that's what happened when I tried it. YMMV especially with a poor quality transformer like a MOT (these have a small air gap due to their welded construction)


Steve Conner