A Case Study on the Signal Delay Effect of Cable Terminations on Time-of-Flight Measurements in GIS

This paper addresses the challenges of locating partial discharge (PD) sources in gas insulated switchgear (GIS), with particular focus on cable terminations. Although the ultra-high frequency (UHF) time of flight (TOF) method is widely used for on-site PD localisation, it assumes a constant signal propagation velocity—an assumption that does not hold in cable terminations due to the presence of multiple dielectric materials. This often results in significant localisation errors and increases the risk of ineffective or unnecessary maintenance.