Saturable Reactors: Power Control with Permanent Magnets

[Jdo300]

Hello,

I've been doing some research into antiquated Magnetic amplifiers. From what I understand, one can use a mag amp to control the power of an AC field by varying the saturation level of whatever core the AC coil is wrapped around (basically). I know that this can be accomplished by using a type of transformer where the control coil is pulsed with DC at varying levels to control the AC coil.

My question is that if it is the magnetic field that controls the power level of the AC signal, and the more saturated the core, the more power can get through. What would that same AC coil do if you wrapped it on a non magnetic core and exposed it to a magnetic field from a permanent magnet placed in close proximity to the coil?

 

[berkeman]

I'm not familiar with mag amps per se, but when you saturate the core of a transformer, you reduce the transfer of energy from primary to secondary, not increase it. Look at the B-H curve for magnetic material...As you get into saturation, the B does not increase in proportion to H anymore. It increases more slowly. That will reduce the flux linking to the secondary coil, compared to what you would get if the material were not saturating.

If you hold a magnet up to a transformer, the transformer does not work well at all.

 

[ravenprp]

Hi,

Thank you for sharing your research on Magnetic amplifiers and their use in power control. You are correct in your understanding that a magnetic amplifier can be used to control the power of an AC field by varying the saturation level of the core. This is achieved by using a control coil that is pulsed with DC to control the saturation level.

To answer your question, if the AC coil is wrapped on a non-magnetic core and exposed to a magnetic field from a permanent magnet, it would not have the same effect as using a magnetic core. This is because the non-magnetic core does not have the ability to be saturated by the magnetic field, therefore it cannot control the power of the AC signal. The magnetic field from the permanent magnet would simply pass through the non-magnetic core and have no effect on the AC signal.

In summary, the use of a magnetic core is necessary for the magnetic amplifier to control the power of the AC signal. Without a magnetic core, the AC coil would not be able to control the power, even when exposed to a magnetic field from a permanent magnet. I hope this helps clarify your question.