Can you use a single phase motor to create three phase power.

[David345]

This might sound like a stupid question so apologies in advance.

So I had a random thought in my head.

So I was wondering if I was to use a single phase motor to spin a three phase generator to create three phase power, would you be able to create more power then the single phase motor is using?

I mean if this was the case then I'm pretty sure someone else would of thought of this idea and used it in the real world. So I guess it probably wouldn't work due to the laws of physics. Or maybe there's a loophole?

And again apologies for the strange question.

 

[johntheo]

Yes, in proportion.

For an ideal generalised generator or motor:
Torque is proportional to current
Speed is proportional to voltage
Mechanical power is equal to electrical power.

Run your car engine at idle and then switch on the rear demist and headlights together, and you will hear the engine note dip slightly, at least for a second while the ECU adjusts the idle valve to compensate. That is the effect of adding about 300 watts of load on the electrical side, absorbing 1/2 horsepower of extra mechanical power from the engine. (Car alternators are rather inefficient.)

It's hardly funfair season now, but go to a fairground, stand by the generator powering a large ride and hear and feel the engine come under load as the ride pulls away. As a generator man and vintage engine enthusiast I have to say there is nothing like the feel of a big old diesel opening its fuel rack to meet the demand. On a showmans steam road loco belted up and driving a ride with a high motor load like an ark, you can often see the governor move in response to every stud of the rheostat.

/dreamy

Or listening to the steam engine slowing down a little when under load from the men throwing the sheaves of corn (after first cutting the binder twine) into the threshing machine drum and then watching the engine man adjusting the speeder spring on the flyball governor to restore the speed , my first introduction to proportional (droop) governing, happy days, many moons ago.