3 phase motor on single phase supply.

[Jackrae]

igotalake
If you give me your e-mail address I'll be able to send you a copy of the diagrams

 

[PaulNorris]

All this experimenting with inductors/capacitors sounds a bit hit-and-miss. resonance in inductive loads can produce some unexpected voltages (and current) in AC power circuits and even if you get it going I suspect power output will be greatly reduced.

Before spending out on inverters and the like I would personally investigate the cost of a single phase motor.

 

[igotalake]

PaulNorris, a single phase motor is not that expensive and may be the right solution but this is a useful thing to know for me as i will probably be buying some other 3 phase kit soon like a power hacksaw and a planer thicknesser so i am now confident that i can run these things without the need of invertors. just need to find some big old caps somewhere and give it a go.

thanks to all involved especially Jackrae for some useful info.

 

[SaladFingers]

i've got a 3hp compressor as well and i've never known of my neighbours having voltage issues. then again my neighbours have got 3 phase supplies. and if we're showing off i've got 2 welders and a plasma cutter!

those videos were very useful and have definitely shown it can be done quite easily. i never thought to look on youtube. my particular motor is for a hydraulic pump on a 4 post ramp so it will start under load so i guess i will need a start cap circuit.

I've got a 2.5hp compressor. Sometimes dips the lights on start up.

 

[igotalake]

Better contact the DNO then

 

[Jackrae]

One thing to be aware of is that if you can get a reasonably sized 3-phase motor up and running, this then gives you a 3-phase supply to run other motors. This technique is often used where several motors need to be run at the same time.

Say you typically want a total of 3 motors to run and their total load capacity is say 2HP (1.5kW) If you have a larger motor, say 3HP (2.2kW) and it's shaft is connected to NOTHING. When you start this large motor and it is running free, you will have a 3-phase voltage generated at its 3 terminals. This motor is now acting as an effective generator and provides a suitable 3-phase voltage to drive your collection of smaller motors.

You may have to switch capacitors in or out of circuit on the large motor to better match its performance to the load motors, but that's no great problem.