FCMA Soft Starter

One is a long proven electronic technology used all over the world with great success and supported by almost every large equipment manufacturer everywhere, the other is a single product from a single supplier in India who keeps having people post "questions" almost exactly like this one every 6 months or so in order to keep trying to legitimize their continued used of a long abandoned technology left over from the days before modern electronics existed.

I wondered why the diagrams and explanation were always the same, from a few different sources! Bit of smoke and mirrors, never quite clear where the second winding power is coming from even in a "university" paper, which also had identical diagrams!

Basically three inductors in line with the three phase lines, as a resistance start. Then it claims an emf from somewhere appears and reduces the inductance. Then the whole thing is bypassed.

If this is a real inquiry, advice....forget FCMA

The basic concept is valid, it's an offshoot of the "Mag-Amp". Years ago Westinghouse & GE used to sell them as motor controllers, but quit when SCRs came along. Mag-Amps are still used, just on motors.

http://www.themeasuringsystemofthegods.com/magnetic%20amplifiers.pdf

Posted that from my iPad, hard to see the mistakes there.

Revision:
Mag-Amps are still used, just NOT on motors.

http://www.themeasuringsystemofthegods.com/magnetic%20amplifiers.pdf

And, MAG-AMPS themselves are an off-shoot of the goodold Saturable Core Reactors that was part of my electrical engineering syllabus way back in 1983. Are we getting back to the 19th century?

A mag amp is basically a saturable core reactor, an inductor with a separate dc winding, like a transformer.

With no dc current the inductor has it's highest impedance so limits the current, a low ac current to the load.

With dc current the core is saturated in one direction so unable to be magnetised back and forth by the ac, the dc offset is too great, so it behaves as a length of copper wire, a low resistance, no impedance, so a higher ac current to the load.

The magnetic characteristics are arranged so that a small dc control current can change a large ac load current, hence "amplifier".

So what are these guys selling?

"So what are these guys selling?"

Just that, a Mag-Amp with an electronic controller on the DC part used as a motor starter, usually only worth doing for very large motors and MV. The DC control has been customized to be a way to slowly ramp a motor up to speed by ramping voltage, just like a solid state soft starter. Like I said, GE and Westinghouse used to sell these in the '50s and '60s, a little bit into the '70s when I started in this business, but dropped the technology once solid state versions came into their own in the '80s.

Their big claim to fame is no power electronic devices and so no harmonics created and "less" risk of failure. But in reality harmonics in a solid state starter are a transient issue anyway, they are only there during ramping which is typically a miniscule amount of operating time. And SCRs are pretty rugged devices in my experience, plus if you isolate them off the grid as pretty much everyone does for MV starters, the risk of failure is likely no greater than whatever contactor is ahead of the FCMA starter. So they are selling this based on perceived problems in my opinion. I think that's why there is only one company in the world who bothers doing it.

We all know that the feedback or compensating winding creates a opposite flux in the main winding to reduce the impedance. but how this feedback winding is connected in soft starter so that it can have a current proportional to the motor counter emf.

Kindly provide is there any available drawing of inside of FCMA soft starter.