Search

The transmission line maintenance is usually carried out by live-line maintenance, and equipotential live-line maintenance is one of the primary forms. In this process, the linemen need to enter the high potential with the help of conductive gloves or a potential transfer rod. This process is called the potential transfer. Because this process is accompanied by sizeable potential transfer current and transient energy, it may threaten linemen’s safety. Hence, the research on this process is of great significance. This paper improves the traditional transient model by introducing the arc model. The finite element method calculates the capacitance distribution between conductors by establishing the three-dimensional models of different postures and positions that the lineman may adopt. Then, considering the influence of the arc model on the process of the potential transfer, the potential transfer current and transient energy under different linemen’s postures and positions are calculated. Finally, the optimal mode of potential transfer operation for linemen in the process of potential transfer is proposed, which provides a theoretical reference for the safety protection of personnel in the process of the potential transfer.

Long air gaps are the main external insulation medium of overhead transmission lines. When there are floating conductors in the air gap, the gap’s configuration changes, and the combined air gaps is formed. We built an experimental platform to obtain the breakdown characteristics of a 2 m rod–plane air gap with a rod floating conductor in different positions under negative lightning impulse. The results show that as the distance between the floating conductor and the high voltage conductor changes, the breakdown voltage (BV) and timing change. Moreover, the breakdown voltage increases with the length of sub-gap 1, showing a trend of first increasing, then decreasing, and then increasing, which is different from the trend under positive lightning impulse. The reason for this phenomenon is inferred from the analysis to be related to the polarity effect.

Ground potential live-line work (GPLW) is an irreplaceable means for the maintenance and elimination of overhead transmission lines. In order to put forward safety protection suggestions for GPLW, the dielectric strength of the GPLW gaps in cup towers and double circuit towers were studied based on a prediction method. The results showed that in both cup towers and double circuit towers, as the gap distance increases, the dielectric strength will also increase. In cup towers, when the lineman is on the side of the window, standing inside the window will increase the dielectric strength of GPLW gaps. When the lineman is at the bottom of the tower window, raising hands will reduce the dielectric strength of GPLW gaps, but this will not happen on the side or top of the tower window. In double circuit towers, the position and posture of the lineman have little effect on the dielectric strength of GPLW air gaps. The results of the study could provide guidance for the live-line work engineering.