The bulk of the industrial market is flooded with 3-phase motors, but yes; there are single-phase VFDs! There are a limited number of manufacturers. At points where three-phase power is unavailable or impractical. A correctly fitted single-phase motors can potentially be a great solution. It is important to note that while using single phase output, your motor may run hot at full load and may need to be de-rated.

Incorrectly fitting a motor can cause repeated motor failure and equipment downtime costing you in the long run. This is why it’s most important to initially size the motor based on your application. Knowing that your application has a single-phase motor opens you up to the option of using a single-phase VFD for control; even if this technology comes with some limitations.

 

These devices are typically horsepower limited(output amps limited) and have very specific compatibility options when it comes to pairing with different types of single-phase motors.

Here’s the list of what motor applications would be considered compatible and not compatible.

Compatible:

  • Permanent Split Capacitor (PSC) type motors
  • Shade Pole Induction Motor
  • Some AC Synchronous motors

Not Compatible:

  • Split Case
  • Capacitor Start
  • Repulsion Induction
  • Any motor with starting switch (centrifugal or relay)
  • Any motor with separate starting winding

Higher HP models are only available if your supply side voltage is 200-240V/1PH/60HZ.  Some manufactures limit their models to one HP while others may go to 5HP.  Horsepower and output current (amps) are going to be the limiting factors with this style for single phase input to single phase output type of VFD.

When trying to decide whether your application would be a good fit for a single-phase option, it’s always good to remember just about every manufacturer has designed this style of VFD around a specific duty load. One manufacturer for Single Phase out/output VFD is LEESONS.

Potential Single-Phase Applications:

  • Fans
  • Blowers
  • Fume Extractors
  • Centrifugal Pump Motors
  • Air Flow Motors