Wide-range ac / dc earth leakage current sensor using fluxgate with self-excitation system

This paper describes an ac / dc earth leakage current sensor using fluxgate magnetic sensor, which provides high sensitivity for wide-range current sensing. The fluxgate current sensor with self-excitation system can be used to detect small ac / dc current of 10mA. Two kinds of detecting which pulse width and pulse frequency could be used in this system to achieve a wide measurement range of 1:1000. These concepts are realized by the simple configuration and low cost sensor, which a toroidal core based on thin-film nanocrystalline soft magnetic material, an excitation coil, and electric circuits.