Explaining complex power

The author discusses the exchange between W.E. Kazibwe in the August 1998 issue and D.W. Knudsen in the October 1998 issue of Power Engineering Review. Kazibwe´s main point is important: the concept of imaginary (reactive) power is a slippery slope when engineers talk to those without a technical background. Knudsen´s main point is equally important: analogies to electrical phenomena can obfuscate instead of clarify. Reactive power, which makes power line voltages sag and substations heat up, is overlooked by most people because it is as difficult to sense as is the similar surging of power in a light bulb. This alternating power is unperceived except by VAr-meters and engineers, as even watthour meters fail to grasp it. A valid analogy from common experience can contribute to a good understanding of the phenomenon, however. Electrical engineers should be able to point out in a simple example the analogs of real power, reactive power, reactive and real power loss, frequency, capacitance, inductance, and various other mysterious electric quantities without needing to resort to the jargon of the “imaginary” or to orthogonal axes