Single Phase Power to Three Phase – Solutions For The Electric Motor User

When someone needs to run a three phase electric motor and only single phase power is available, they look for a solution. There are a couple options to go from single phase power to three phase. This article will discuss options available for going from single phase power to three phase., pros and cons for each option, and, links to our website for products that will go from single phase power to three phase. There are two different methods to go from single phase power to three phase:

  • Variable Frequency Drives (VFD’s)
  • Rotary Phase Converters (RPC’s)

When going from single phase power to three phase, either a variable frequency drive or rotary phase converter is required. Variable frequency drives come with a number of different single phase input for three phase output options. Variable frequency drives that go from single phase power to three phase are available in a wide range of voltage and power ratings: From 120 Volt single phase input for 240 Volt three phase output, up to 1.5 horsepower; To 208-240 Volt single phase input for 240 Volt three phase output, up to 3 horsepower.

Variable frequency drives can also be derated to run three phase motors above 3 HP from single phase supply. Derating a VFD allows customers with 208-240 volt single phase power the ability to run 240 volt three phase equipment. Derated VFD’s are available up to 20 HP for 208-240 Volt single phase supply. Derating a VFD incorrectly for single phase supply can be easily avoided by contacting an experienced technician before purchasing equipment.

Rotary phase converters (RPC’s) will change single phase power to three phase but RPC’s are heavy and use many moving parts. RPC’s are old technology but RPC’s will be around for years to come because some applications that go from single phase power to three phase cannot use a VFD; VFD’s can go from single phase to three phase for electric motor driven applications; but RPC’s can go from single phase to three phase on applications with and without electric motors.

Single phase motors cannot be used on variable frequency drives. When customers with single phase motors want to control the speed of their electric motor, the only option available is to replace the single phase motor with an equivalent three phase motor, and then apply a variable frequency drive to that three phase motor. For VFD and RPC repair and replacement quotes, contact Precision Electric.

 

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