UC Santa Cruz

A prototype was designed, built, and tested that uses split-core current transformers to harvest electrical energy. These transformers can be easily attached around the AC lines of nearby machinery without interference to the electrical supply nor requiring the work of an electrician. This system requires virtually no maintenance as the endpoint energy harvesting devices require no batteries and can transmit messages periodically using energy harvested and stored in a capacitor bank. This system is able to take periodic measurements from a low energy Bluetooth transceiver, installed on a harvestable AC line carrying a minimum of 420mA (RMS) of current. Measurements increase in frequency as the harvested load power increases, and with the use of a prototype current transformer with a laminated steel core continuous operation with a 1.8v output can be acheived from as little as 6.25A. This continuous operation allows for sampling rates as high as 12kHz. The system itself draws no more than 250µW from the AC line it harvests from. These characteristics make the proposed system highly suitable for power measurement in important practical applications.