Threephase Power In The Real World

Three-phase power has many uses from appliances such as refrigerators, to welders, transformers, ovens, computers, CNC mills, oil rig pumps and just about anything else you can imagine being powered by electricity. Three-phase by its very nature is a much more smooth form of electricity as compared with single-phase power. It is this more consistent electrical power that allows machines that use it to run more efficiently and last many years longer than their relative machines running on the other phases. Some applications are able to work with three-phase power in ways that would not work on single-phase at all.

The alternator in your family car is a three-phase device with a rectifier circuit nearly the same as the one you built in this experiment, except its diodes are far more powerful. Commercial versions of wind driven alternators also use three-phase power exclusively including electronic circuitry to automatically switch between Wye and Delta windings depending upon the wind conditions. And, of course, the high-voltage power lines you see marching across the landscape are three-phase as well.

Then there are wide varieties of power electronic circuits that are used to control three-phase motors like the one here made by Anacon Systems, Inc. Electronic modules like their EagleDrive 3 motor controller have taken over many of the tasks that mechanical systems performed in the past to keep motors running smoothly and at top efficiencies.

Figure 6-23

The EagleDrive 3 motor by Anacon Systems, Inc.

Photo © Anacon Systems Inc., used with permission.

Figure 6-23

The EagleDrive 3 motor by Anacon Systems, Inc.

Photo © Anacon Systems Inc., used with permission.

There are also applications that demand three-phase power from single-phase, which is what this unit from Isomatic does. Isomatic manufactures single phase to three phase converters using electronic switching and an internal motor-generator with 600% overload capability. These units are suitable for farms, workshops, etc, where the site lacks three-phase supply and within large buildings where all 3 phases are not close to the equipment location.

Figure 6-24: An

Isomatic Singlephase to three-phase Converter

Photo © Isomatic; used with permission.

Figure 6-24: An

Isomatic Singlephase to three-phase Converter

Photo © Isomatic; used with permission.

With all the three-phase power generating equipment available, how about something to measure it? That's exactly what the 355 Harmonics Analyzer, a hand-held three-phase power and harmonics analyzer manufactured by Dranetz-BMI does. This instrument measures true three-phase harmonics and power. An ideal tool for industrial plant engineers and utility power quality engineers, it lets you make quick, accurate judgments about overheated neutral conductors, transformer derating, and equipment specification.

Figure 6-25

The Dranetz-BMI 355 Harmonics Analyzer

Photo © Dranetz-BMI; used with permission.

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