FCMA Starter

I can't find this question in my textbook... what chapter and page are you looking at?

Students should rely on Google for things their professors can't answer:

http://lmgtfy.com/?q=FCMA+Starter

You will not find much on FCMA starters outside of India, where there is only one company making them. It's essentially an offshoot of an old forgotten technology (as far as motor starting) called a Magnetic Amplifier, or "Mag-Amp". Mag-Amps are still used for a variety of things, but although both GE and Westinghouse used them in the 40s and 50s, once solid state soft starting technology became less expensive the technology was dropped because the Mag-Amps were huge and expensive. This company in India resurrected it again a decade ago, modernized the amplifier circuit a little, claimed it is "new" and that it offers benefits over solid state. But that is debatable and if you are not IN or near India, long term support for a product made by a small company like that makes it less than attractive.

If you ARE in India or it's sphere of influence, it might be worth investigating if you have some particular dislike of solid state soft starters, but otherwise, I don't see the tangible benefits.

As to it's application to a slip ring (Wound Rotor) Induction Motor, that will depend entirely on your PURPOSE for having the WRIM. If it is being used strictly as a way of soft starting the motor, then you can EITHER use the FCMA or a Reuced Voltage Solid State (RVSS) soft starter to accelerate it by using just one step of resistance, then shorting out the resistor at full speed. Neither technology can safely accelerate the WRIM with the rotor shorted, there will be too much rotor current for the given torque and the motor will not survive long.

But if you are using the WRIM as a method of continuous torque and/or speed control, neither the FCMA nor the RVSS will do that for you. For that, you will need a Vector Control capable VFD. Then because the VFD is capable of total control of the flux, torque etc., you CAN just short out the rotor circuit. But do so ON the rotor, not the rings, because wear on the brushes will affect the motor performance over time.

Side note: It seems to me that about at least once per year, someone posts a "question" about FCMA starters in this forum. It's my long held suspicion that these posts are shills for the company behind it, to get free advertising as to it's existence by bringing it up in forums.