Analysis of leakage current characteristics during aging process of SiR insulator under uniform and longitudinal non-uniform pollution conditions.

• Leakage current magnitude decreases under longitudinal non-uniform pollution. • Leakage current magnitude increases with increasing the aging time and humidity. • Phase angle of leakage current is analysed based on the insulator pollution level. • The non-uniformity of pollution distribution has little effect on the phase angle. • Increase of humidity leads to a slight decrease in the phase angle. This paper presents the comprehensive analysis of Leakage Current (LC) of a silicone rubber insulator under uniform and longitudinal non-uniform pollution conditions based on a large amount of test data. The experimental tests are carried out under different humidity levels for un-aged and aged samples. The results obtained indicate that the LC harmonics magnitudes increase with increasing the salt deposit density, aging time, and humidity, while they decrease with increasing the pollution non-uniformity degree. The analysis of phase angle difference between LC and applied voltage (θ I - V °) demonstrates that the θ I - V ° is in the range of 54.3°–60.4°, 20.1°–32.5°, and 7.5°–11.8° under clean condition, light pollution and moderate pollution conditions, respectively. In addition, the θ I - V ° is less than 2.3° under heavy pollution condition. The non-uniformity of pollution distribution and insulator aging time have very little effect on the θ I - V ° , while the increase of humidity leads to a slight decrease in the θ I - V °. [ABSTRACT FROM AUTHOR]