ABSTRACT
Electrical metering deals with two basic quantities: energy and power. Energy is equivalent to work. Power is the rate of doing work. Power applied (or consumed) for any length of time is energy. In mathematical terms, power integrated over time is energy. e basic electrical unit of energy is the watthour. e basic unit of power is the watt. e watthour meter measures energy (in watthours), while the wattmeter measures the rate of energy, power (in watthours per hour or simply watts). For a constant power level, power multiplied by time is energy. For example, a watthour meter connected for 2 h in a circuit using 500 W (500 Wh/h) will register 1000 Wh.
