Partial discharge characteristics in phase domain for various cylindrical voids

As the shape and the size of a void in a insulation system affect considerably the progress of the deterioration of the insulation performance if partial discharges (PD's) occur in the void, it is important to estimate both of the two parameters. Conventional PD characteristics are however ineffective to estimate the shape of a void. Therefore the relationship between the shape of a cylindrical void and the statistical characteristics of PD's occurring in the void is investigated in terms of Φ-q distribution profile as well as conventional PD characteristics such as the maximum apparent discharge magnitude (qmax). The Φ-q distribution profile describes the average pulse height as a function of the phase angle of an applied AC voltage and was found to be sensitive to the structure of a void in which PD's occurred[1].