PROXIMITY-BASED PASSIVE CURRENT SENSORS FOR REAL-TIME MONITORING OF POWER USAGE IN LOW AND MID-VOLTAGE APPLICATIONS

摘要

Traditional monitoring of current flow in power lines involves breaking the circuit for through-the-sensor type monitoring or separating individual wires for around-the-conductor "clamp" metering. Such techniques for measurement are invasive and disruptive for many applications. Using 0.9 cm diameter permanent magnets attached to piezoelectric bimorph elements in conjunction with the fluctuating magnetic fields generated by alternating currents, sensors have been developed that enable in-situ, self-powered measurement of current flow without the need to encircle or disconnect the wire being measured. Whereas previous development of these devices has focused on two-wire applications for low (<600V) voltages, single-wire configurations for higher-voltage (up to 15kV) applications are also considered here.Outputs have been found to be linear through a wide ranges of current (0-200A on 0.6-120V AC), with resolution limited primarily by sensor distance from the target wire (3cm or less from wire edge). Sensitivity studies have been performed on conductors of varying dimensions (18 gauge to 4 gauge) and geometries (single conductor and two-wire) for known sensor placements and current flows. Initial integration has been performed with a wireless radio device to produce a self-contained sensor package 8cm by 10cm by 3cm that can sample data at 2 kHz and transmit results to a base station for further analysis.Initial numerical modeling of the magnetic field gradients around current-carrying wires has been performed to optimize sensor placement. Potential applications include customer(home, business, industry) and distribution grid-level monitoring.