Current Transducer Based on Thermoformed Piezo-Magnetic-Electrets

Thermoformed tubular channels piezoelectrets exhibiting piezoelectric-magnetic behaviors were recently presented as thermoformed magnetic-piezoelectrets (TMPs). This alternative sensor was suitable for detecting external magnetic fields from distant magnets. In this contribution, TMPs transducer was investigated as current transducer (CT), where the magnetic field produced by an electrical current passing through a energized wire mechanically stimulates the TMP and consequently disrupts the electrical charge equilibrium providing a proportional electrical signal. The charge variation was correlated with the magnetic field intensity, providing a piezomagnetic coefficient, similar to those noted in traditional piezoelectrets. It has been noticed that under certain conditions, TMP could have coefficients up to $498\times {10}^{{5}}$ pC/T. From these results, it was concluded that such a polymer-based device is suitable for monitoring electrical current in live wires, providing an interesting solution for noninvasive CT with a reduced footprint. These novel transducers can, thus, provide an effective replacement for coil-based CTs reducing installation cost and space, without the need for wire reconnection (as required by the coil-based CTs), enabling hot-plug capabilities, as well as providing a direct and cost-effective replacement for high-frequency current transformers.