Electromagnetic radiated field measurements for partial discharge diagnostic

Recently, improvements have been made in the diagnostic of electrical insulation systems by means of electric Partial Discharge (PD) standard measurements through a stochastic approach in the treatment of the acquired data: in this way, the identification of the defects as well as the separation of multiple defects simultaneously active, have been successfully performed. However, the standard PD measurement process can be affected by the well-known parasitic effects due to conducted noise whose spectrum can have characteristics similar to those of the measured signal. Moreover, the classic PD measurement system have to be suitable assembled on the Device Under Test (DUT) so determining a complex erection on site operations, which can force the temporary outage of the same DUT and the related equipment. In the aim of overcoming the previous limitations of the classic PD measurement system, in this paper a novel approach for the characterization of the defects in a dielectric material is proposed. It is based on the remote measurement of the ElectroMagnetic (EM) transient field radiated from PD. In order to validate the approach, the standard CIGRE I test cell is used. Different test measurements with different spatial sensors location enable to obtain the PD diagnostic. A comparison with standard electric current-voltage PD measurements has been carried out with a good agreement in terms of diagnostic results.