Electrodeless Piezoelectric Based Sensor for Electric Field Measurement in High Voltage Applications

Piezoelectric materials produce a strain when an electric field is applied due to the converse piezoelectric effect and have been used to develop electric field sensors. However, the existing designs use materials with electrodes and/or external circuitry which are not suitable for installing in areas of high voltage. This paper investigates the strain produced when electrodeless piezoelectric material is placed in an ambient electric field for the purpose of developing electric field sensors to perform in situ condition monitoring of HV assets. Simulations showed that single crystal piezo PMN-PT, generated sub-micro-strains when exposed to electric fields in the range typical of overhead line insulation. A 10mm x 5mm x 0.5mm block of PMN-PT, without electrodes, was attached to a fibre Bragg grating strain sensor and placed in a uniform electric field generated by a pair of parallel copper plates. The deformation measured by the FBG sensor attached to the PMN-PT block exhibited a high linearity with the applied electric field in the range 0.07–0.59 kV/mm. The results show that the converse piezoelectric effect in electrodeless piezoelectric material can be quantified by a high sensitivity strain sensor and once calibrated can be used to develop fully dielectric electric field sensors suitable for embedding within or around HV assets.