DEVICE FOR DETERMINING DIRECTION OF INSTALLATION OF CURRENT TRANSFORMER IN WATTMETER

PROBLEM TO BE SOLVED: To provide a device capable of easily determining whether the phases of voltage and current in a wattmeter are in a correct relationship with each other or not. SOLUTION: The device for determining the direction of installation of a current transformer in a wattmeter to measure electric power through the use of voltage taken out of electric supply line and current taken out of the electric supply line via a current transformer is provided with a voltage input terminal to be provided with the voltage, a current input terminal to be provided with the current, a multiplier M to compute an electric power value by multiplying the voltage provided for the voltage input terminal by the current provided for the current input terminal, and a display LED to perform visual display when the electric power value, which is the output of the multiplier M, indicates a predetermined polarity.