The rising cost of electrical energy is causing many plant engineers to install meters to measure consumption of various processes and equipment, assess efficiency, and help find ways to reduce energy costs. The measurement of electrical energy consumption is accomplished with a watt-hour meter, which, when properly connected between the power source and the load, integrates the power with respect to time. Two basic facts apply to properly used watt-hour meters. Each revolution of the meter disk is equal to some finite number of watt-hours; the exact value depends on the meter's rating. The speed of the disk is proportional to the watts drawn by the load - the greater the load, the greater the speed. Watt-hour meters are available in three basic styles: socket connected, bottom connected, and back connected (switchboard style). The article discusses these meters, as well as standard meter ratings, demand measurement, pulse-operated demand equipment, and other aspects of the subject.
