Design of the Internal Fuse Dimension for HV Shunt Capacitor in UHV Transmission Projects

The internal fuse plays an important role in the protection of high-voltage (HV) shunt capacitors. However, there is still a lack of research on the design of the internal fuse for HV shunt capacitors. In this article, an experimental platform is built to investigate the effect of the diameter on the fusing characteristics of the fuse. The maximum nonfusing current action integral and the minimum fusing current action integral of fuses with different diameters in the range of 0.3–0.7 mm are obtained. Then, the equivalent circuits of the capacitor unit are analyzed when there is a short between terminals or element breakdown. The current flowing through the fuses with different diameters and lengths is studied, and the current action integral is calculated. Comparing them with the maximum nonfusing current action integral and the minimum fusing current action integral obtained from the experiments, the selection range of fuse diameter and length can be determined. In order to verify the rationality of the fuse design method, the internal fuse of a 668 kvar HV shunt capacitor used in ultrahigh-voltage (UHV) transmission projects is designed and validated experimentally. This article will provide a reference for the internal fuse dimension design of HV shunt capacitors.