Phase Converters & Power Factor
Phase Converter Efficiency
Installing a Phase Converter
Rotary Phase Converters
Static Phase Converters
VFDs as Phase Converters
     • Harmonic Distortion
Three-Phase Motors
Phase Converters & Voltage Balance
Phase Converter Applications
     • Submersible Pumps
     • Woodworking Equipment
     • Dual Lift Stations
     • Phase Converters & Welders
     • Phase Converters & CNC Machines
     • Phase Converters & Air Compressors
     • Phase Converters & Elevators
     • Phase Converters & Wire EDM
     Phase Converters & HVAC
Phase Converters & Transformers
     • Step-up Transformers
     • Buck-Boost Transformers
     • Isolation Transformers
Phase Converter Experts
Digital Phase Converters
Regenerative Power
Three-Phase Power
     • Delta vs. Wye Configured Power
Motor Starting Currents

Phase Converters and HVAC


Many of todays heating/cooling systems are using inverter driven compressors coupled with energy saving control systems for optimal performance. These systems frequently are only available in a 3-phase power configuration. When 3-phase power is not available, a phase converter may be the only solution for this HVAC application.

VFDs used as a phase converter are not a good solution for this application. When a VFD is connected to a piece of equipment which contains three-phase motors as well as other controls, it is very likely that both the VFD and the equipment would be damaged. If multiple loads are connected to a VFD with individual contactors for each separate load, the VFD may not be able to handle the current surges which occur when

individual loads are switched on and off. Also, if there were any capacitors in the equipment connected directly across the VFD outputs, the VFD would have to shut down immediately or be destroyed by the extremely high currents that would flow when the output voltage pulses were applied to the capacitors.

Rotary phase converters may not be a good solution as well. The widely variable load of modern HVAC equipment exposes the primary weakness of rotary phase converters, namely, the inability to maintain balanced voltage. A rotary phase converter can provide balanced voltage at only one load point and the more variable the load, the worse the voltage balance. Also, standby power consumption of a rotary motor running constantly may be cost prohibitive for the HVAC application.

A digital phase converter may be a practical and effective solution for 3-phase HVAC systems where utility 3-phase power is not available. A true digital phase converter produces sine wave voltage, making it safe to power the electronics in the machine. Digital phase converters are capable of handling multiple load demands and maintain voltage balance under all load conditions. A digital converter has no moving parts, so there is no starting current to cause line disturbances. Electronic power factor correction allows it to operate at unity power factor and does not consume reactive power. In fact, it supplies the reactive power needed by any loads it operates, making it a very utility friendly converter. The converter operates at 95-98% efficiency and when energized with no load consumes very little power.