Prediction method of breakdown voltage of long air gaps containing a floating conductor

The maintenance of power transmission lines is often carried out through live working to ensure the uninterrupted power supply of the power systems. When the worker enters the high potential area from the ground potential, it forms a floating potential conductor, which affects the air gap discharge characteristics in the transmission lines. Studying the discharge characteristics in this condition is directly related to the safety of the workers. This article builds a long air gap experimental platform with a floating potential conductor to simulate the actual working conditions in live working. Finally, the positive switching impulse breakdown voltages with the floating potential conductor in different longitudinal positions are obtained. The results show that the existence of the floating potential conductor will affect the breakdown voltage of the air gap, and there is a position with the lowest breakdown voltage. Furthermore, considering the disadvantages of the high cost of the full-scale test, this article uses experimental data to establish a mathematical model to predict the breakdown voltages. By comparing the predicted value with the experimental value, it can be found that the model has good adaptability and can be used to predict the breakdown voltage in this condition.