Everything we know about the power system, whether for control, or planning, or billing, is the result of a measurement, so the measurements ought to be good. The authors of Measuring the Electric Grid: Mysteries Explained pull no punches in showing how bad today’s measurements are, and how to make them better.Misunderstandings about important power system quantities, especially reactive power, apparent power, and phasors, are pervasive. The first four cha...