Definitions & Guidelines

Phase conversion solutions

3-phase Motor Loads

A three-phase induction motor has 3 sets of windings. When supplied with three-phase AC voltage, the uniform alternating (120 degree) separation between the wave forms will create a balanced rotating magnetic field that spins the motor. A three-phase motor can spin driven by only two of the three windings but cannot start spinning without all 3 or mechanical assistance to break it free of the initial locked rotor condition.

Static Phase Converter

In the simplest implementation, a static phase converter is effectively just a form of motor starter. The converter taps a leg of the single-phase supply and feeds, after adjusting the phase timing with capacitors, the third winding of the motor to help break it free of the locked rotor condition. After startup, the motor continues to run on two of the three windings, with a resulting decrease in power and efficiency.

Rotary Phase Converter

In the most common configuration, a rotary phase converter works using a three-phase induction motor started by a static phase converter. Once the motor is running on two legs of a single-phase supply, the third winding within the motor creates the third leg in a similar fashion to a generator.

Phase Perfect^® Phase Converter

The Phase Perfect^® uses digitally controlled switches (IGBT’s) to take power as needed from two legs of a single-phase supply and rectifies it to charge a DC bus. A Phase Perfect then uses additional switches to convert the DC back into an AC waveform to generate the third leg. This digital phase conversion is actively controlled by a microprocessor. Because the system is microprocessor-controlled, the generated leg is continually optimized to provide balanced power and protect any attached equipment.