Problems in starting synchronous motor in a pump station 3

[Bronzeado]

Hi folks,

A 5.5 MW, 6.9 kV synchronous motor did not start when it is energized. Then we moved the rotor position and the motor starts. We have observed that the motor only runs if the rotor is in a particular position.
I wonder if anybody has faced a problem like that.

Best Regards,

Herivelto S. Bronzeado
Brasília, Brazil

http://www.linkedin.com/profile/view?id=46319837&trk=tab_pro

 

[edison123]

Hi Bill

Since synch motors have a larger air gap than the normal wound rotor motor, it is not an easy conversion. The air-gap in a synchronous induction motor is taken care of at the design stage.

Also, since the DC current in one phase is twice that of other two phases, a straight conversion will result in rotor overheating in that phase unless the copper size is increased for that phase.

Here are some pics of the 3.3 KV, 2000 HP, 12 pole synch induction motor rotor we are currently rewinding at our shop showing the different slot sizes and slipring sizes.

Muthu

http://www.edison.co.in

 

[edison123]

Dratz. Sorry, didn't mean to post such big pics. Don't know how to resize them now.

Muthu

http://www.edison.co.in

 

[ScottyUK]

Idle curiousity - where did that motor originate? My guess is either Rugby or Trafford Park, but I could be way off the mark.

 

[waross]

Thanks Mutu
The pics seem OK in my browser. It often has issues with oversized pics.
Yours
Bill

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[ScottyUK]

I've just noticed the number of blowholes in the rotor casting.

 

[edison123]

Scotty - It's FLS make. I don't think the company even exists any more. Yes, there are many blowholes in the rotor wheel casting but they are only superficial. The cross arms are over two inch thick.

Muthu

http://www.edison.co.in