Teaching Three Phase Electrical Power Using A Low Voltage Power Source

The United States Air Force Academy teaches a first course in Electrical Power Systems. While computer simulations and modeling techniques have become pervasive throughout most of the engineering curricula, and while the utilization of computers in the classroom and the laboratory represents a major pedagogical improvement, a hardware-based approach to teaching several electrical power distribution and usage topics can also be very effective. Our course includes several laboratory experiments and demonstrations designed to involve the student in the learning process. A locally designed and manufactured three-phase, low-voltage, variablefrequency power supply is used to teach parts of this Electrical Power Systems course. The threephase low-voltage system enhances student safety while allowing for student involvement in the learning process. Additional laboratory time also leads to numerous other learning opportunities for the student. This paper discusses the utilization of the three-phase low-voltage power supply as a teaching tool. A discussion of several laboratory experiments and demonstrations is included. Some of these demonstrations, for example, slowing the power supply frequency to the point that phase rotation is visible without the use of electronic test equipment, cannot be accomplished using the more traditional high voltage “power bench” type equipment. Finally, the limitations of the three-phase low-voltage power supply are discussed.