Breakdown characteristic of solid-solid interfaces

Breakdown properties of dielectric interfaces play an important role in insulation coordination in different high voltage power and pulsed power systems. Solid-solid and solid-fluid interfaces are critical topological elements of various insulating systems.

Lower breakdown strength of the interfaces may put additional requirements on solid, liquid and gaseous insulating topologies and materials. Also, stricter environmental protection regulations and requirements lead to a wider use of the dielectric materials with lower environmental impact, for example gases/fluids with lower green-house impact factor as compared to that of SF6; or ester-based insulating liquids.

However, the breakdown characteristics of solid/fluid interfaces and interfaces which include environmentally friendly fluids in particular, are not well known and require further systematic investigation. The dielectric behaviour of such interfaces may significantly influence the operational performance of different power and pulsed power high voltage systems.

With further progress in the development of compact high voltage systems, it is important to minimise their dimensions and weight of insulating materials used in such systems. Thus, specific topological parameters of the insulators and interfaces between different insulation materials in critical components such as HV connectors, insulating supports, barriers and other elements of the high voltage systems are important for footprint and weight optimisation. The growing demand in advanced power and pulsed power systems with higher power ratings, elevated voltage levels and reduced footprint require thorough investigation of the dielectric behaviour of solid-solid and solid-fluid interfaces.

The present project will address these challenges and will be focused on the systematic investigation of the high voltage breakdown characteristics of different solid-solid and solid-fluid interfaces stressed with high voltage impulses with various rates of voltage rise. Solid materials which are commonly used in high voltage engineering practice will be investigated.

An experimental study of the breakdown behaviour of interfaces formed by different solid materials will be aimed at comprehensive investigation of their impulsive breakdown characteristics under ambient and elevated air pressures. Potential effects of moisture and voltage wave-shape on the breakdown behaviour of the dielectric interfaces will be also investigated.

The project also will include investigation of the interfacial propagation of transient plasma formations across solid/gas interfaces in order to characterise the dielectric properties of such interfaces formed by solid dielectrics and different environmentally friendly gases including air and nitrogen.

The project will include an analytical part which will be aimed at the analysis of transient pre- and post - breakdown processes across solid-solid and solid-fluid interfaces which will underpin the theoretical analysis of different breakdown properties of solid-solid and solid-fluid interfaces.

The proposed programme offers a systematic approach to investigation of the breakdown characteristics of the dielectric interfaces stressed with different high voltage signals. As a result of this project it is planned to generate information and knowledge which will be important for optimisation and coordination of practical insulation systems for pulsed power and power applications. The results of this project will help in further development of advanced high voltage power and pulsed power systems with low environmental impact and minimum footprint.