Triple point surface discharge photography in atmospheric gases using Intensified high-speed camera system

In this paper investigations of surface discharges using an ultraviolet (UV) intensified high-speed camera system are presented, accompanied with high frequency response and resolution current recordings. A needle-plane electrode configuration is employed for the generation of a strongly non-uniform electric field on the surface of disk-shaped insulator samples made of polytetrafluoroethylene (PTFE) or epoxy resin. The electrode arrangement is further insulated by a gaseous medium of either technical air (21% O2/79% N2), nitrogen (N2) or carbon dioxide (CO2). An alternating (AC) voltage waveform at power frequency (50Hz) is maintained at levels sufficiently below the flashover voltage corresponding to each presented case. Detailed descriptions of the technical specifications of the utilised equipment are provided for both optical and electrical measurements in the experimental set-up. The obtained results demonstrate the discharge propagation during the AC-cycle and its dependence on the insulator type and gaseous insulating medium. Individual surface discharges are captured in the microsecond range to describe the discharge morphology based on the generated current pulse and instantaneous applied voltage level. Back-discharges on the insulating disc are also discussed, and a relevant image capture is presente

Creeping discharge development over insulator surfaces in natural gases: Design and implementation of test procedure

Creeping discharges are strongly related to the presence of triple junctions in high voltage equipment. Their occurrence represents a common and important issue in compressed gas insulated systems. So far, many experimental studies available in the literature are dedicated to the characterisation of this phenomenon under the variation of different system parameters such as insulator geometry and material, voltage waveform, gas type and electrodes configuration. This paper deals with the development of discharges over insulator samples of different materials using natural gases, under AC voltage waveforms for a point-plane electrode arrangement. Results from a simulation of the electrode configuration which calculates the initial field conditions are also presented. The results shown in this paper constitute a preliminary part of a future extensive research programme

Enhanced partial discharge evaluation through integrated RF and IEC measurements

In light of growing regulatory concerns regarding the environmental impact of SF6, it is crucial to develop diagnostic procedures that can identify defects in systems utilising alternative gases for insulation. This study examines the application of carbon dioxide and technical air (N2/O2, 79%/21%) in high-voltage applications. Partial discharge assessment is a well-established technique for condition monitoring, commonly employing conventional (IEC 60270) and radio frequency techniques. Simultaneously measuring partial discharge using both radio frequency and electrical detection methods might yield valuable insights into the shape of the fundamental current pulse, which would otherwise be unattainable by merely relying on one methodology. This paper describes the integration of radio frequency and conventional measurements to evaluate the partial discharge properties of technical air and carbon dioxide gas insulating medium. Distinctive patterns become evident when plotting the energy of the radiated pulse versus apparent charge for a particular defect source. These patterns may appear as either curved or clustered data. The integration of the two measurements offers the opportunity to leverage the respective advantages of each approach while mitigating certain limitations that arise when relying solely on one method of measurement