design for magnetic amplifier

[anit_y]

hi everyone,

i want to design a magnetic amplifier which will control load of 1KW at ac winding,
and can be controlled by dc voltage of 12v with 100ma current using control winding of magnetic amplifier
plz suggest me the stepwise procedure to design such magnetic amplifier.

waiting for reply..

 

[tcmtech]

So what do you know and what are you using it for?

It was and still is a common device in some arc welder power supplies and large line power regulation systems.

 

[Mr RB]

You won't get full 0% -> 100% control of the 1kW, and you will probably need a lot more than 1.2W at the control winding. It will also require a specially constructed transformer even larger than a typical 1kW transformer which is almost a foot square and costs $$$.

It sounds like a poor idea both in terms of cost and effort compared to a cheap little 1kW triac based controller.

 

[anit_y]

So what do you know and what are you using it for?

It was and still is a common device in some arc welder power supplies and large line power regulation systems.

thanks for u r reply,

information i know about magnetic amplifier is a device used to control large power using small power, by varying small power at control winding large power can be controlled at load winding.

i am doing one project in that i want to control the luminance(or intensity) of street light and as per my knowledge it can be controlled using magnetic amplifier

 

[tcmtech]

Controlling HID type street lamp intensity is very limited because of the nature of how they work. The light output can be reduced a little but the efficiency suffers greatly for it with most common types.

A 20% drop in light output may mean a 50% loss of working efficiency in some designs plus a substantial loss of working life as well so there is no actual savings or bulb life gains by doing so.

As far as a magnetic amplifier two 2:1 or 4:1 isolation transformers set up in series with the higher voltage windings carrying the DC current and the two lower voltage windings put in series with the load can work to a reasonable degree as a basic magnetic amplifier.

The two DC winding are limiting the magnetic fields in the AC side by only letting the limited amount of current flow in one direction and nearly non in the other direction due to inductive reactance. The AC windings need to be in series and the two transformers are then ran 180 degrees out of phase from each other so that one blocks one half of the AC wave and the other blocks the other half of the AC wave.

Its not an ideal magnetic amplifier circuit but it is functional non the less! The control voltage and currents are rather unknown though. It will have its least limiting effects when the DC current through higher voltage primary's are ran at their maximum rated current levels.

If you can find a schematic for the old Miller TM series welders you will see exactly how the magnetic amplifiers are used in the output to regulate the voltage or current levels.
I dont have them on my present computer now or I could post one.