Three Phase Power
Derived from Single Phase

If you need three-phase power at your home or farm but only have single-phase power available, there really is no solution as good as having three-phase power brought in. But if you insist on running a three-phase machine on single-phase power, you will need a phase converter. These can be purchased from companies such as this one.

There is a "home-made" option which can be cost-effective if a large three-phase induction motor can be obtained at a near-salvage price. Use a small single-phase motor to spin up a large three-phase motor. Next, energize one phase of the three-phase motor with the single-phase power. Then switch off the single-phase starter motor but leave one phase of the large three-phase motor connected to the single-phase source. The large-three-phase motor will now be acting as a motor-generator, with one phase motoring to make the rotor spin and the other two phases generating power. After the motor-generator is started, one may connect a smaller three-phase machine in parallel with the large motor, which is now will acting as a motor-generator combination.

The motor used as a motor-generator in the homemade solution needs to have the correct voltage rating and wye or delta connection. For example, in North America many three-phase machines require 208 V, but the single-phase power is supplied at 120 or 240 V. In this case the ideal motor for use as the motor generator would be a 208 V wye connected motor with four terminals, A, B, C, and N. Then 120 V single phase power can be applied from A to N and terminals B and C will generate the other two phases. The resulting three-phase power will be at 208 V, line-to-line.