There are a few conciderations
Is this motor required to run in both directions? In three phase it is done by swapping two of the phases. In single phase it's a bit more difficult.... but it can be done.
or
Does this motor run a hydraulic pump? this only requires it to run in one direction.
Is this motor required to start under load?
It would probably need to be a 4 pole single phase induction motor. When we look at a single phase motor, it is a really a three phase motor but it uses capacitors to derive the other two phases by utilising the phase shift phenomena of a capacitor.
The problem with this method is that it is not very efficient compared to a three phase motor. The power factor is only 0.7 e.g a 4KW single phase induction motor actually consumes 5.6KW
They also do not like starting under load, it may run all day at it's maximum load rating but getting it there is another problem.
When a motor starts, it can draw up to 6 times its running current until it gets up to speed. This will eventually knock out your main fuse which will take some explaining to your electricity provider.
To start a single phase motor successfully you need a softstart unit, like a Fairchild HFE2. This will analyse the current drawn by the motor and limit the voltage in sympathy to the rotation speed and dramatically reduce the start up current .
There doesn't seem to be many manufactures making soft start units for single phase motors above 3KW.
The other alternative is an inverter starter, this means you do not have to change your motor, it's a box which goes between the supply and motor. It's more expensive than a soft starter but by the time you've changed the motor and bought a soft starter, you would probably find it's cheaper to buy just the inverter.
