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. The basic electrical unit of energy is the

watthour. The basic unit of power is the watt. The 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

two hours in a circuit using 500 watts (500 watthours per hour) will register 1000 watthours.