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Don Ross
Don Ross • Jan 12, 2015

Running a 3 phase motor on a single phase electrical circuit.

Running a 3 phase motor on a single phase electrical circuit. Can anyone tell me how it is done? It's important if you have a piece of machinery in the field that requires or needs it out of necessity to operate. I have done it. It's not Vudu. Think young people, know the knowledge of your grand fathers not just the text books of your school. Think how can this be. What is poly phasing? How can you manipulate it. Mechanical /electrical / DDC systems use all sorts of ways to control things. If you want to be the bright star of the future, think out of the box. That's how new technology is created.
lal
lal • Jan 12, 2015
The usual objective is to create a rotating magnetic field. That can be partially achieved by powering two of the windings in parallel and attaching a series capacitor to one of them, as in a single phase induction motor. Theorotically, that should create a rotating magnetic field and probably make the rotor start rotating at a very low speed which gradually might increase but way too less than the rated value. The windings will be exposed to immense current flow and it wouldn't take much long before they get damaged/burnt usually.

Yet another way would be to rotate the rotor manually and while in motion, switch on the input supply that is connected to any one of the windings. Low RPM, rough rotation and high current flow - not feasible again!

At any cost, these methods should be avoided to operate a three phase machine which otherwise would bring severe damage to the windings or other connections. A three phase machine is designed to be operated in a three phase supply.
Don Ross
Don Ross • Jan 12, 2015
I used a inverter I bought and it required a motor off to the side. It can be ,, or could of been purchased in the past. But technology fades away and knowledge is lost. then we start all over again reinventing the wheel so to speak. Please search for that inverter or what ever it is. Bring it out of the dark. I ran a refrigeration compressor on it that had a high start torque. Thanks.
lal
lal • Jan 12, 2015
May be you could explain a bit about the type of inverter and connections you made. It seems to me that you used a three phase inverter for the purpose or am I missing something?
Don Ross
Don Ross • Jan 12, 2015
It's been years so I will look into it and let you know. But from what I remember the created new leg went through the motor to create the offset. It might of been as simple as that. Let me look into it. I actually thought some one would of been familiar with the application. You know the old timers. But many here are very young. I will work on it. It is interesting though. Thanks,,, later
Don Ross
Don Ross • Jan 12, 2015
I found this on YouTube but sounds more complicated than I remember doing it.
There's a simpler way so we need to find it. Who is willing to research YouTube and boil it all down.
A guy said Quote:
Don't use capacitors,its easy if you have a slit phase 480 volt supply common in Australia for farms where 3 phase is too expensive I rigged a setup for a guy that repaired old cars using a transformer to drop the 480 to 430,then a 3/4 horse pony motor was coupled by vee belts to a 30 hp Brush motor,used to feed a10 6 and 5 horse motors,by contactors driven by a24 volt winding on the transformer the pony is started then once the output motor is up to speed contactor 1 drops out closing contactor 2 which supplies A and C phase B being generated by transformer action the pony then acts as a flywheel,all three motors running 422 volts delivered perfect for 415 volt motors allowing for voltage drop etc
Don Ross
Don Ross • Jan 12, 2015
I also found this. I guess there are several ways to do it. Not sure whos right.
But this guy says he's an electrical engineer.
Quote
You almost got the right answer; except that you don't need any idler motors. I run my 3hp. LeBlonde 17" lathe on single phase, only with the addition of motor run type capacitors. so can you. I do have an unfair advantage, I'm a graduate electrical engineer so I actually understand what's going on here. Switching the capacitor from one power line wire to the other does reverse. the lathe has normal power in forward and reverse. some experiementation will be required to get the useful mfd. in capys. but this is very cheap. they are available from surplus houses. get the ones rated for 600vac, as the capacitor voltage is often over 400 volts on a 220 supply. So now t he right answer is available on U-tube; for a wonder.
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lal
lal • Jan 13, 2015
Well capacitor, I mentioned that in the first post too. A capacitor can make a phase difference of around 90 degrees when connected in series with the supply. A winding with a series capacitor would be enough to develop a rotating magnetic field when shunted with the non capacitor seriesed winding. For an induction motor to be self starting, you need a rotating magnetic field which can be achieved this way. Anyway, cannot expect rated power output from the motor in this method.
Don Ross
Don Ross • Jan 13, 2015
Your a sharp guy. Now start a web site and sell them to people out in the field as side hobby lol That's beyond me. But i believe it's needed out in the fields and factories.
Help the ones struggling with trying to produce with limited funding and means.

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