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Operating a three-phase motor using single-phase power

Publication date: 
August 2016
Chuck Yung, EASA Senior Technical Support Specialist
Type of media: 

We all have that occasional customer who got a “deal” at an auction: a compressor, or lathe, or wood-working equipment, only to discover when he started to install it that this equipment has a three-phase motor and only single-phase power is available. Maybe it’s your neighbor or a friend from church. In any case, you know that you are about to be called upon to “convert” that piece of equipment, and you probably realize that it’s going to cost you more than you can charge.

Solutions previously used include:

  • Connecting two phases to the incoming 220V single-phase power and using capacitors from one energized lead to create a “phantom leg” for the third lead.

  • Use a rotary phase converter.

Fortunately, there is a better way to solve this dilemma. Because a variable frequency drive (VFD) rectifies each pair of phases to DC, then inverts the DC power for the three-phase output, a VFD can be used with single-phase input power to operate a three-phase motor.

Download the article below for the details.

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