424 / 2022-03-15 21:43:43

Surface partial discharges at DC voltage on electrical construction materials under variable gas pressure

electrical construction material,variable gas pressure,DC partial discharges

Purpose / Aim

Well-known isolation materials, e.g. fiber composites for electrical constructions, are highly optimized for the use in AC voltage applications. The isolation performance of specific construction materials is unknown for DC applications in most instances. To qualify these materials for their suitability in high DC field strengths, additional studies are performed. AC voltage qualified materials are usually designed with a low loss factor and resistance against partial discharges. Therefore, special coatings or surface treatments are used. Under the influence of DC voltage stress, these materials can build up surface charges, which influence the development of partial discharges.



Experimental / Modeling methods

To quantify this influence, measurements are carried out. Surface partial discharges are measured in an autoclave with variable forms of electrodes, gases and gas pressures. Characteristic parameters as the time between discharges, amplitude of the apparent charge or evaluation of the pattern above the inception voltage are recorded and evaluated for positive and negative test voltages. A comparison of the known AC performance to the determined DC performance is scheduled.



Results / Discussion

A different behavior of known construction material under DC-influence is observed. A feasible explanation are long-time polarization-effects in the isolation materials and a corresponding non-linear change in the field distribution. Time-dependent effects are expected in scheduled measurements.