How to Run a 3 Phase Motor on Single Phase Power

Motors usually come in two different types, single or three phase. The number of phases on the motor is determined by how the motor is wound. It is easy to find out how many phases your motor has by looking at one of two factors.

First, you can check the motor nameplate data which is usually located on a paper or metal label attached to the side of the motor. Second you can simply look at the number of electrical leads coming out of the motor. If your motor has three black leads and a green lead then it is likely three phase. The three hot leads are usually labeled U, V and W and the final lead is labeled ground.

Running a three phase motor on single phase power is simple. First you’ll need to invest in a variable frequency drive. We recommend using the GK3000 Series Variable Frequency Drive for multiple reasons. The GK3000 is simple to setup and easy to wire. It also comes standard with a NEMA 1 enclosure which gives basic dust and water drip protection. Most importantly, for the purposes of this post, the GK3000 comes with a number of different single phase input options up to 20 HP.

Essentially all you need to do is wire the single phase power to the input side of your variable frequency drive and then wire the three phase power of your motor to the output section of the drive. That’s it! You can check out our videos for basic steps about variable frequency setup.

Many people contact us and are disappointed to find out that single phase motors don’t really get to very high horsepowers for variable frequency drives. They can also be frustrated that there are not really many options for those who are using 480 VAC or 600 VAC power. The truth is there are very few applications out in the world that require single phase to three phase conversion, the majority of cases we run into are typically individuals attempting to use their household power to run a 3 phase motor, such as a milling machine.

Another option, but usually more expensive, for running a three phase motor from single phase power is the purchase of a rotary phase converter. Rotary phase converters are great because they can generate a clean three phase signal from single phase power. The biggest problem people run into with this solution is, as we said before, the cost associated with doing so. It rarely makes sense to do this since most people who are converting single phase to three phase power are usually doing so for smaller motors.

A third, and not frequently used, option is to get three phase power from a generator. Many people don’t consider this as an alternative. Propane and gas generators can generate clean three phase power to run three phase motors. This is a great solution for those who are needing a portable or emergency setup for their motor setups.

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