Study on the Impact of Secondary Cable Length on Port Interference in Sensitive Devices

The very fast transient processes induced by the operation of gas-insulated substation (GIS) switches may result in significant electromagnetic interference or even damage to secondary cables and the connected equipment. To quantitatively investigate the relationship between the length of secondary cables and the amplitude of the disturbance voltage on the secondary side, experiments has been conducted on a 220 kV GIS prototype simulation platform. The results indicate that as the length of the secondary cable increases, the overall amplitude of the disturbance voltage on the secondary side decreases. The amplitude of the low-frequency (${\lt}1 \mathrm{MHz}$) component of disturbance voltage is essentially unaffected by the length of the secondary cable, while the amplitude of the high-frequency ($\gt1 \mathrm{MHz}$) component generally decreases with the increasing of the secondary cable length. The research findings of this paper can provide effective reference for quantitative suppression of the disturbance voltage on the secondary side.