Need to know about VS motor

[ahsan_i_h]

Hello everyone,

I would like to know about VS motor. This type of variable speed motor is not a combination of VFD with induction motor nor it is a DC motor with speed controller. Perhaps it is an induction motor but different approach in speed control. I only heard the description of it. Also I tried with few books and could not find any information according to its description. The picture below matches with its description.

Thanks in advance.

 

[Dan Mills]

Could be a separately excited DC machine, you turn the field current DOWN to cause it to speed up....

There is a whole world of electrical machines out there, some of them very clever and predating sand based controls, a book on electrical machines from 80-100 years back is fascinating reading.

Regards, Dan.

 

[ahsan_i_h]

Thanks for reply. This type of motors are still used in some old factories. I have found some information from this website http://www.motor21.net/vs.htm .From this website a connection diagram is found like the picture below.



According to the picture three phase supply is going to an induction motor(IM) and speed control setting is done from VS motor controller box. So it is not a DC motor. I am wondering how the speed control mechanism works.