An Analysis of a Clamp-on Current Sensor with Zero-flux Method

Current measurements over a wide frequency spectrum must be performed when installing semiconductor power conversation facilities in industrial equipment. We proposed a current sensor with a wide frequency range based on the ac zero-flux method. In this paper we analyze the mechanism of operation of such sensors. In particular, we derive a theoretical formula of the operation by giving priority to the CT operation in the magnetic circuit. We developed a clamp-on current sensor with a wide frequency range of 1 Hz to 500 kHz and good accuracy within ±0.5%. The analytical results agree well with experimental data for the prototype sensor.