looking for IGC's (induction generator controller)

[werner]

Hi all,

using an induction motor to generate electricity is attractive, but it needs a good system to control voltage and frequency. IGC's do that job by diverting extra energy to dump loads.

Are there any suggestions for sources of IGC's?

regards,

Werner

Argentina

[bill541]

Hi Werner,

I think you have to spin an induction motor slightly faster than its design speed to get it into self excitation and start producing electricity. For this reason I would think the frequency would always be on the high side.

Maybe some of the motor experts on this forum may know of a way to change the field excitation to help regulate the voltage output and maybe make it cut in at a slower rpm.

Bill

[TomW]

Werner;

I don't know exactly how but somewhere I think you picked up either some wrong information or misinterpreted some information. An induction generators [at least those discussed here] frequency output will be directly related to rotational speed of the generator. I believe open circuit voltage is also. Capacitors figure in somehow, also.

I don't have the patience to attempt an explanation but felt someone should point this out. I think if there was such a thing as your "IGC" I would have heard of it and this is the first time I have seen it referred to. Of course the governor / speed control on a gas powered generator might be considered an "IGC" so who knows? Acronyms in this field come and go and don't always mean the same thing to everyone.

Just my opinion and not necessarily held by others and subject to misinterpretation of course.

T

[Joseph Turrisi]

Werner if you havn't done so yet try a search for IGC's on the net. I did a quick one and found several page about them. I would like to recommend a book titled MOTORS AS GENERATORS FOR MICRO-HYDRO POWER ISBN# 1 85339 286 3. This book covers  the advantages/disadvantages, motor selection, excitation capacitor requirements and much more when using induction motors as generators.

[Joseph Turrisi]

Bill I think you are getting IG's confussed with PMA's. An induction generator is a induction motor that is spun faster than its rated rpm to produce power but it is not self exciting. It requires excitation from the power grid or from capacitors to make any power.

PMA's are self exciting and make power using magnets and make power at any rpm.

[Joseph Turrisi]

Tom in your reply to Werner you said (I think if there was such a thing as your "IGC" I would have heard of it and this is the first time I have seen it referred to) maybe I am reading this the wrong way but it sounds like you are saying that since you have not heard of it it doesn't exist. May I suggest that you get and read the book I suggested to werner. In its simplist form the IGC(induction generator controller) controlls the voltage of a induction generator by increasing or decreasing the power dissipated in a ballast load.

[TomW]

As I said:

Just my opinion and not necessarily held by others and subject to misinterpretation of course.

Seems he mentioned frequency control also.

T

[bill541]

No confusion here Joseph,

If you have a small capacitive load on the motor and spin it past its normal operating RPM, the residual magnetism in the rotor can self excite the induction motor. Several folks do this, especially with 3-phase induction motors.

Paul Cunningham wrote a nice little article on the subject if anyone is interested.

http://www.microhydropower.com/staffpubs/staff4.htm

Bill

[werner]

Thanks for the link Bill, as well as all the comments by others.

Motors-as-generators is new to me, seems an exiting field. One advantage is that they come in multiple poles, say 8, which makes them rotate slow, and may aleviate need for gear boxes/pulleys. For hydro, they are also tolerant to run-away speeds.

Regulation is by monitoring voltage which at the same time keeps frequency in check. The equivalent in generators would be the ELC which monitors frequency.

I have a contact for England and another for Australia which sell IGCs commercially. My question here aimed at also finding outlets in Canada/USA.

More later,

Werner

[robl]

Just a quick note to say that I used the book referenced in the previous post to modify a Hyundai 1 hp/3 phase/220VAC motor into a single phase/240VAC generator using capapcitors.

The unit is self excited and stays close enough to 60HZ that a neighbour is running his lights and a small stereo directly from the wheel. Note that I use a 1KW load diverter to ensure the load does not go over 260VAC at the wheel. The voltage can droop but that is just a matter of reducing loads.

Cheers

Rob