EUROTECH-G&PS

Solving the single to three-phase dilemma

Electric motors up to three horsepower are usually made for single-phase power. Larger motors requiring currents beyond the usual 10-amp limit for power outlets are therefore made for three phase power.

Some properties, streets or districts are, for economic reasons, only connected to one of the three phases. If you intend to use three-phase equipment, compare the cost of providing three-phase supply (such as transformer and power lines) with the one-time investment in a single to three phase Booster converter.

“ The daily or monthly line charges in New Zealand can be very high,” says Eurotech Machinery’s Helmut Holighaus. “Saving on line charges may pay for the cost of a converter in a few years.”

The power demand of three phase equipment often exceeds the capacity of typical household sockets. The installation of a three phase Booster converter with a throughput larger than four kW requires an industrial single phase wall switch-socket combination for 32 amps or higher. And because electric motors draw high start-up currents, the wire size between the fuse box and single phase power outlet needs special attention. There are other limiting factors for the use of high power Booster converters above 12 kW: the capacity of the distribution transformer sitting on a pole near a property and the wire sizes between such a transformer and a house or workshop. Holighaus recommends that people consult their electrician.

Who needs a Booster shot?

Booster converters are ideal for three phase machines in engineering workshops – typically welders up to 400 amps, lathes, grinders, milling machines and saws. In automotive workshops Boosters can handle loads from car hoists, welders and wheel balancers. Typical three phase loads also come from panel saws, planers, thicknessers, spindle moulders, guillotines or combination machines – as well as larger kilns and industrial washing machines, refrigeration systems, cranes and conveyors. Some applications are confined and require Booster components to be integrated into the overall design. Inside the wall of refrigeration containers, for example, or inside three phase floor grinders converted into powerful single-phase ones.“ Different applications require a different quality of power,” explains Holighaus. “Standard electric induction motors, for example, are very forgiving. They are designed to run in developing countries where voltages and phase symmetry are not always perfect. The other extremes are inverters, large variable speed drives and power supplies of CNC machines: they often are sensitive to voltage fluctuations and asymmetrical conditions, and therefore ideal for the Booster converter.” Booster single to three phase converters are assembled in Cambridge and Hamilton and sold worldwide. Outputs range from two kW to 32kW for the local market, and four kW to 100kW for the US market. There’re models for IEC conditions with 380-415V three phase at 50 Hertz (European, Asian and Pacific) and NEMA conditions with 220-240V three phase or 440-480V both at 60 Hertz (North American).