ELECTRONIC WATT HOUR METER WITH LARGE DYNAMIC RANGE

摘要

PURPOSE: An electronic watt hour meter with a wide dynamic range is provided to expand the measuring range of a load current in the input range of an analog/digital converting part by turning off a part or whole of relay switches in connection with respect resistors. CONSTITUTION: A voltage converting part(110) is in parallel connection with power and detects a supplying voltage. Detected supplying voltage is converted to output a converted voltage. A current converting part(120) converts a supplying current, which is adjusted according to a controlling signal or detected according to a pre-set conversion ratio. A converted current is outputted. An analog/digital converting part(130) converts the converted voltage and the converted current into digital signals. A calculating and controlling part(140) calculates power and watt hour and controls conversion ratio by outputting a controlling signal to a current converting part.