Phase Power Primer

American Rotary (AmericanRotary.com, is a Wisconsinbased company making rotary phase converters since 1991. Here are there tips to make the most of your shop machining equipment. Phase here refers to the distribution of a load. Single-phase power is a two-wire alternating current with one phase wire and one neutral wire, with current flowing between them. Three-phase power is a three-wire AC power circuit with each phase AC signal 120 electrical degrees apart.

Residential homes are usually served by a single-phase power supply while commercial and industrial facilities usually use a three-phase supply. Although many types of machining equipment operate off three-phase power, owners of this equipment often don’t realize what this means until it’s in their shop. But a lack of proper three phase power can prevent you from getting the equipment you really need, properly setting up the equipment you already have, or expanding in the future so that you can grow your business.

Whether you operate a full-time shop or tinker in your garage on the weekends, many manual and CNC mills and lathes can be powered by a rotary phase converter that doesn’t require a custom building with three-phase power preinstalled. A good rotary phase converter can provide voltage balance, reliable start-up, and scalability. For voltage balance, CNC phase converters rated for three-phase CNC applications maintain at least a +/-5% voltage balance.

Unbalanced voltages from non-CNC phase converters can be hard on the equipment, causing undesirable conditions such as excess noise and poor performance. Rotary CNC phase converters can be used on any type of equipment, especially voltage sensitive machines such as CNC milling machines, lathes, PLCs, EDMs and any other type of equipment that relies on balanced input power provided the converter is rated for the kilowatts (k W) that the machine requires.

Phase converters have had a reputation of drawing a huge inrush current upon start-up, resulting in dimming neighbors’ lights along with demand charges from the utility and increasing power bills. Phase converters with variable impedance technology built in drastically reduces this for reliable start-up and with no voltage drop. Additionally, a phase converter should be rated to run single or multiple motor loads.

By selecting a converter with precision balanced from a "no-load" condition, you don’t need to worry about running a small motor together with larger ones using the same phase converter. More importantly, it should also be able to operate with no load engaged for an indefinite period, so you don’t have to worry about damaging your unit while your equipment loads are not operating. One of the great things about phase converters is the ability to scale your energy use as your shop or business grows.

High-quality phase converters are capable of phase synchronization for increased capacity to double, triple, or quadruple your power.