A phase converter changes single-phase power to three-phase or vice versa. In today's world, most, if not all, home appliances operate on single phase power. Units that operate on 240 volts in residential settings, such as clothes dryers and stoves, use single-phase power because three-phase power is not cost-effective on small, residential electric motors. In rural areas where three-phase power distribution is monetarily untenable, rural residents, such as farmers and workers in other agricultural industries, need three-phase power to run their large, self-starting motors and must rely on phase converters. This is also true for anyone who wants and/or needs three-phase power.
There are three types of phase converters generally available today:
Digital
Rotary
Static
Rotary converters have three terminals for the flow of electric current. Any two of them will run together on single-phase power. The third terminal is connected to a separate motor called an idler, which is started using stored capacitance. Once the idler spins into phase with the other two terminals, three phase power comes out of the converter.
Digital converters rely on a digital signal processor, which regulates the flow of power into and out of the converter. The processor draws power from the single-phase input and uses that power to charge a series of direct current capacitors. Once the capacitors are charged, the processor sends the current through a series of insulated gate bipolar transistors to convert the power back to alternating current. This alternating current charge runs the third motor, which, when spun up to speed, provides the three-phase power.
Both of these options are much more expensive than the third option: a static phase converter. This type of converter simply uses a capacitor to get a three-phase motor going by joining with a single-phase input. Once the motor starts, the third terminal goes dead to prevent damage to the capacitors. Because only two of the three terminals are charged, the motor should only be run at 2/3 power. Although less efficient than other converters, static converters are inexpensive and easy to maintain.