SOLID STATE ELECTRIC POWER USAGE METER AND METHOD FOR DETERMINING POWER USAGE

摘要

2120912 9307500 PCTABS00021 A digital solid state electric power usage meter for determining power usage by a load (13) attached to an electric power network (12). The meter has a current sensor (16-18) coupled to each phase of the electric power network for sensing current in each phase, a voltage divider (35) coupled to each phase of the power network for detecting the voltage level on each phase, an analog to digital (A/D) converter (60) coupled to the current sensors (16-18) and voltage dividers (35) receiving signals from the current sensors (16-18) related to the current in each phase and signals from the voltage dividers (35) related to the voltage on each phase. The A/D converter (60) samples the current and voltage related signals at predetermined times at a rate which insures that samples of the current and voltage related signals do not repeat for a large number of cycles of the network frequency. A processor (62) calculates instantaneous values of power from the digital signals and a memory (34) accumulates the instantaneous values to form a value representative of electric power usage.