Can some one explain in details how a 3 phase motor can be converted into 1 phase motor.?

Rewinding it as told before, you will lose some power in the conversion.

Up to 3 hp, you can consider an inverter 1x220 to 3x220 (or whatever you have in your country) and changing the star-triangle bridges, you'll be able to have a true three phase motor running from a single phase line.

Inverter can be more expensive than buying a new monophasic motor.... I have to mention this too.

The easiest way is too run it thru VFD inverter much cheaper no HP loss that what we do on rural lift Sta

Agree,no need to convert the motor, simply use a VFD. Gives you the benefit of using a three phase motor which is more economical and reliable. The added benefit of a VFD should your application allow you to vary the load to save energy.

Thank you all for your concern,I really apreciate it.but i have three phase verticals pumps.single hase pumps are mostly used in this market.i want to sellt hese pumps after doing the conversion.but i cant understand why some of you suggested VFD.
my intentions are not energy saving instead stock clearing.I hoe you all inderstood what I meant.....?HELP ME........!.!!!!

A single phase 230v VSD will give you 3 phase out. There is a limit in kw's, by the manufacturers in the 230v range. Possibly have the motors rewound. Tried a few years ago with the help of a motor rewinder, he fitted capacitor to the motor with some internal changes. The motor was inefficient and burnt out after 2 months.

There are two ways to convert a three phase motor to single phase.
Rewinding the motor is one, you will loose power, as more iron pack is required on monophase motors for the same power.
The other way is to use an inverter, which will give you 3x220 volts instead of 3x380 volts (or whatever voltage you have, read the data in your motors) . You will have to re arrange the connections from star to triangle. This works for 220-380 motors, up to 3 hp appox.
Technically an inverter may or may not be VFD, nowadays all inverters do have VFD cappabilities as well as slow start. You may use them or not.
But this is the way to achieve your requirement. Remember: up to 3 hp.