Energy scavenging technique for powering wireless sensors

A capacitive scavenging device is proposed to extract energy from the electric field that surrounds the equipment in a substation. Related research has shown that switching techniques can be used to increase the useful power obtained. An experiment has been set up by putting two parallel plates of 10 cm radius in a uniform AC electric field up to 20 kV/m. A mechanical reed relay was used at this stage to provide a high dasiaOFFpsila resistance. Tests were carried out by switching the relay at different frequencies and varying the length of the switching pulses. Initial results show that introducing switching could improve the scavenging efficiency compare with the basic linear circuitry. The proposed device could enable simple sensors to be energy self-sufficient, opening the way for wireless sensors to be installed widely in the power grid.