METHOD AND APPARATUS FOR DIGITALLY MEASURING AMOUNT OF ELECTRIC ENERGY CONSUMPTION

摘要

PURPOSE: To provide a digital watt-hour meter which has a more appropriate accuracy and can be manufactured at an allowable cost. CONSTITUTION: A time differential coefficient of a magnetic field generated by a current flowing through conductors 11-12 of a transmission line is measured by magnetic field change rate pickups 16 and 17, instead of measuring the current actually from the conductors 11-12, and thereby a record being proportional to the time differential coefficient of the current is obtained. By using a suitable microcomputer 30, the time differential coefficient of the magnetic field (magnetic field change rate) is expressed by an algorithmic series for expressing a periodic phenomenon, such as a low-order Fourier series, in a stage 40. The microcomputer 30 converts a mathematically the time differential coefficient of the current expressed by the algorithmic series and measured values of voltage from the conductors into a power record and computes an approximate value of the quantity of electric power consumption (stages 41-43). Moreover, the power records are summed up, in the stage 43, so as to obtain a numerical value being proportional to the quantity of energy consumption.