induction regulators 2

[awtt]

Dear Friends, Someone told me it is possible to convert a slip ring motor into a variable voltage transformer? If so what would be the set-up. I am wanting to change a 500 HP. 6 pole slip ring motor into an induction regulator so I can vary the voltage from zero upwards. The motor is 416v 3 phase with rotor voltage of 480v 50 cycle .Thanking you if you could help , Regards . William Tyree

 

[Skogsgurra]

Yes. Use the fact that a WRIM's slip-ring voltages are phase rotated when rotor is turned. Add the secondary voltage to the grid (transformer needed) and use the resulting voltage for your load. One restriction is that you cannot connect this voltage to anything that uses the grid as a reference without considering what the phase-shift may do.

See attached pdf.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[Skogsgurra]

Addition to the above: It is possible to run without transformer if the rotor voltage fits the grid voltage. Then just connect rotor to grid and use stator (six wire connection needed) to buck/boost the grid voltage.

Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[starkopete]

Hi,
Maybe this will help

 

[electricuwe]

Gunnar's statements on this topic are correct, but I'd like to add two aspects:

- If you buy new equipment using this approach these transformers are not derived from standard induction motor designs, but purpose built.

- If you convert an existing machine into such a variable transformer, consider that you need an independent blower to provide sufficient cooling at standstill.

See bottom left picture, text unfortunately not available in English:

http://www.asa-trafo-bau.de/contdeu/produkte/flgkt/index.htm