A Resonant Galvanometer for Noninvasive Passive Wide-Range AC Monitoring

Noninvasion, low-power consumption, and wide-range measurement of sensor nodes in wireless sensor networks remain a large challenge for smart grid and Internet of things (IoT). A noninvasive passive range-adjustable resonant (Wang) galvanometer (RGM or WGM) is proposed in this work to provide a new solution to the challenge of sensor nodes. In resonator-based principle, magnetic fields generated by current to be measured are converted into vibrations via sensing units, and further converted into output signals via detecting units. A prototype of the proposed RGM is fabricated to demonstrate the three main features of noninvasive, passive, and range-adjustable measurement. A wide-range measurement, varying from milliamps to kiloamps, can be achieved and adjusted with different sensitivities by optimizing RGM design and positioning space configuration. Taking a single-phase ac current as a typical demonstration, a high sensitivity is obtained in amp range with near an order of magnitude increase compared to the state of the art. Different from all existing current sensors in principle, in addition to the abovementioned three main features, potential advantages of high flexibility and strong diversity in resonator-based principle of the proposed RGM, are applicable to a variety of diverse current measurements in multiphases and multiwires.