Most high-voltage power lines, including those leading directly from power companies, carry three-phase electrical power. Three circuit conductors carry electrical current; each of these alternating current conductors achieves peak current at a phase shift of 120 degrees from the other two phases. This produces consistent and constant current delivery for utility power grids and to provide the electrical current needed to run large machinery and equipment.
The power lines that lead to private residences and small businesses, however, typically carry single-phase electrical current at 240 volts or less; in some cases, split-phase current is used to provide greater stability for home and small business applications.
Homes and businesses that receive single-phase power or split-phase current at 240 volts may not have the electrical power necessary to run equipment that includes:
- Light-duty drill presses
- Table saws
- Small metal lathes and milling machines
- Other operator-controlled equipment that can be operated at lower-than-maximum horsepower ratings
Static phase converters are the solution.
Static phase converters are ideally suited to provide initial three-phase power for starting machinery driven by 3 phase motors of less than 10 horsepower in size.
Built around a voltage sensitive relay switch and one or sometimes two capacitors, a static phase converter provides the starting current required of the third phase. During initial start-up the first capacitor discharges it stored energy to the third phase. After the motor starts the relay disconnects the first capacitor. The motor continues to operate on single phase energy. Typically under such conditions, the motor will operate at approximately 60 percent of full rated power. If the static phase converter is equipped with a second ‘run’ capacitor which balances the voltage to approximately 50 percent load, performance increases to approximately 70 percent rated full rated power.
Limitations of Static Phase Converters
Three-phase electrical tools will not operate at top speed and efficiency when powered by single-phase power augmented by a static phase converter. Without the help of the converter, however, that equipment would not function at all.
Also, static phase converters cannot be used for heating loads. They cannot split a single-phase supply into three separate real voltages and currents. That phase-shifted output voltage can start and run a motor, but it cannot produce a current through a resistance heater.
Attractive Option for Home and Small Business
For many homeowners and small business operators, static converters can provide a low-cost and effective way to provide adequate power for restaurant equipment, carpentry applications, machine shop tools and other common power equipment around the home or business. By opting for these economical converters to manage the power needs of these tools, consumers can enjoy added functionality from their existing electrical system.