A Power Scavenging Current Transformer to Remotely Power ‘Bird on Wire’ Sensors in Grid Monitoring

This paper presents the design of a current transformer that is used for scavenging power from an 60 Hz ac transmission line. The primary goal of the design is to maximize the scavenged power under minimum line current conditions of a few amperes to power sensor in a smart grid network. Impedance matching is shown to be critical to obtain maximum power. An experimental test bed was setup to verify the design. A current transformer with a ferrite core was used with 450 turns of 28 AWG copper wire can deliver 9.5 mW of power at a line current of 1.54 A. The load circuit consists of a bridge rectifier and a low drop-out regulator designed to charge a 4.0 V NiMH battery pack.