A novel inductive electromagnetic energy harvester for condition monitoring sensors

As the operation of electrical power networks becomes increasingly sophisticated, the role of condition monitoring is expanding. The burden of implementing additional condition monitoring will be eased if self-powered, fully autonomous sensors can be used to reduce installation and maintenance costs. Changing batteries is inconvenient and standard mains power is often not available where sensors are needed. Existing commercial inductive harvesters to power sensors must be fitted around high voltage transmission lines, which requires either a power outage or live line installation. In this paper, an alternative harvester is presented which can be installed at any location where there is sufficient magnetic field. Magnetic flux densities within a cable tunnel are considered, from which a suitable target is defined for the magnetic flux density range over which the harvester must provide power to the sensor. optimisation of output power per unit volume limits cost and allows placement of sensors in locations with restricted space. Coil parameters to achieve high output power per unit volume are discussed and experimental results are presented that demonstrate effective energy harvesting. A coil design for a typical cable tunnel is proposed.