How to Make a Simple Rotary Phase Converter

Written by adam fonseca
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How to Make a Simple Rotary Phase Converter
A rotary phase converter can be built using a generating motor. (motor image by Klaus Eppele from

A rotary phase converter, otherwise known as an RPC, is an electrical machine that amplifies and produces a current of electric power from a single-phase power source into three-phase electric power. These converters are helpful in running large electrical machinery when needed. You can make a simple RPC with relative ease in your workshop or home by using the proper equipment, knowledge and tools.

Skill level:

Things you need

  • Three-phase motor
  • Electrical wires
  • Rope
  • Generator or idler
  • Safety glasses
  • Work gloves

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  1. 1

    Use electrical wires to connect 230-volt single-phase power from your generator or idler to the T1 and T2 supply terminals of the motor you are using as a converter.

  2. 2

    Get the motor rotor spinning by wrapping your rope around the motor shaft and pulling the rope to turn the shaft. The motor will not start on its own.

  3. 3

    Disconnect the three-phase power of the T-terminals on your motor, which should now run on its own.

Tips and warnings

  • Depending on the size of your equipment, you may require a higher horsepower in your idler or generator to power the motor during this process.
  • For best results you should use a generator with 20% to 30% higher horsepower than the motor of the equipment you will be using.
  • Size your wires and connections according to the amount of power you will be converting to the motor.If your wires are too small, the conversion will not work properly and the motor will not turn over.
  • Due to the amount of power and voltage involved in powering a motor during this process, be certain to wear safety glasses and protective work clothing to prevent injury. If you are unsure about the voltage required to power your motor or how to connect your wires to the T-terminals, do not continue the project and speak to a licensed mechanic for more information.

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