Effect of Temperature on Creeping Flashover Voltage of Nanofilled Oil-Pressboard Insulation

Abstract

Creeping flashover (surface discharge) at oil-pressboard interface is considered a serious failure of the insulation system in power transformers. In this paper, creeping flashover voltage at oil-pressboard interface using the concept of nanofluids is experimentally evaluated. The creeping flashover test is carried out using a needle-plate electrode configuration considering 5 mm gap spacing. Three different types of nanofiller (CuO, MgO and ZnO) with different concentration levels (0.05, 0.1, 0.2 g/l) are used for enhancing oil-pressboard creeping flashover voltage. The effect of temperature on creeping flashover voltage is experimentally studied for all nanofiller types at the adopted concentration levels. The considered temperatures are room temperature (30°C), 50 °C, 80 °C and 120 °C. These temperatures are considered to study their effect on creeping flashover voltage taking into consideration a wide range of transformer loading. Average of ten creeping flashover voltages is investigated for all studied conditions. Also, Weibull distribution is used for analyzing the creeping flashover voltages at 10% and 50% probabilities for the studied conditions. Finally, interpretations of the obtained results are presented through a proposed mechanism.

Keywords

• Creeping flashover voltage
• oil-pressboard
• nanoparticles
• CuO
• MgO
• ZnO