Transmission lines the world over often have to traverse mountain ranges or plateaus situated at least 1000 m above sea level. In China, for example, it is estimated that some 60% of the country lies at this altitude or higher.

Building overhead lines and substations that perform reliably for decades has always been a challenge. Many things can go wrong over such a time frame, especially given increasing pollution, more weather extremes linked to climate change, growing interactions with humans and wildlife – all potentially culminating in problems linked to flashover, mechanical or other types of failure.

Thermal imaging has for years served as a practical and cost-effective means of assessing the condition of surge arresters. But comparatively little effort has been made to determine what constitutes a ‘healthy’ versus a ‘suspect’ surface temperature profile.

The focus when it comes to components and equipment used on power grids has traditionally been on cost and performance.

Bushings are key components of HV substation equipment such as transformers and switchgear, allowing conductors to transfer energy from one insulating medium to another. Most typically, this is from an oil or SF6 insulation environment to air.

Not long ago, a HV cable termination operating in a Mediterranean country experienced catastrophic failure, sending high velocity porcelain shards in all directions.