A Power Factor Correction Demonstration Unit for Agricultural Electricity Instruction

Abstract

Power factor and power factor correction are among the most difficult electrical concepts for Agricultural Systems Technology students to learn when taught in an abstract, mathematical manner. This article provides relevant background on these concepts and describes the development, construction, and technical evaluation of an inexpensive power factor correction demonstration unit designed to provide meaningful hands-on instruction in these concepts. The demonstration unit incorporates a selectable capacitor bank that allows students to observe the effects of incrementally added capacitance on circuit voltage, current, true power, and power factor while operating a 120-V shaded-pole motor under no-load conditions. Performance evaluation demonstrated reliable operation of the unit and repeatable electrical measurements across four replications at each of seven capacitance levels. As capacitance increased, power factor improved from 0.57 to 0.95 while current decreased from 0.72 to 0.43 A. Additional capacitance resulted in overcorrection, causing power factor to decrease and current to increase while true power remained essentially unchanged. The demonstration unit provides an inexpensive, portable instructional tool that enables students to visualize the effects of power factor correction and overcorrection in real time, supporting experiential learning in agricultural electricity courses.