Pressboard

About: Pressboard is a research topic. Over the lifetime, 1123 publications have been published within this topic receiving 9089 citations.

Flow electrification in power transformers: electrical modeling

Abstract: A charge zone named electrical double layer exists at a solid-liquid interface. The liquid flow induces a phenomenon called flow electrification: it generates a streaming current (caused by the convection of charges present in the liquid) and a potential rise in the solid (if this one is insulated from the ground). These potentials may reach values high enough to produce electrical discharges and provoke accidents. Although this phenomenon has been identified a long time ago, its physical description rests unknown (production and displacement of charges, equilibrium, etc.). As part of the research program of Electricite de France, a prototype sensor dedicated to flow electrification characterization at the interface between pressboard and oil has been developed with the University of Poitiers. In this paper we propose to use an electrical analogy to model these processes in the prototype. This electrical model is based on the analysis of experiences carried out with the sensor.

Understanding impact of copper sulphide diffusion into pressboard insulation in transformers

Abstract: Surface discharge inception voltage (SDIV) in copper sulphide diffused Oil Impregnated Pressboard (OIP) material reduces with increases in harmonic content in the supply voltage, irrespective of Total Harmonic Distortion (THD). The rise time of current signal injected during Surface discharge process is about few ns and the Fast Fourier transform (FFT) analysis of Ultra High Frequency (UHF) signal formed due to surface discharge process have dominant frequency of 0.9 GHz. The characteristics are the same irrespective of level of thermal aging of OIP and amount of DBDS present in transformer oil. The amplitude and width of the current pulse increases with increases due to aging. Atomic Absorption Spectroscopy (AAS) studies results indicate that the amount of copper content in pressboard material have increased with increasing in concentration level of DBDS. Energy dispersive spectroscopy (EDS) conform the amount of copper and sulphur is high with thermally aged OIP due to aging of OIP in transformer oil with DBDS concentration. Attenuated Total Reflectance - Fourier Transform Infrared (ATR-FTIR) spectroscopy studies indicates the formation of aldehydes and carboxylic acids, caused due to degradation of cellulose structure. Phase Resolved Partial Discharge (PRPD) analysis indicates that the surface discharge activity occurs near the peak of the applied AC/harmonic AC voltages at inception voltage and at rising portion of the applied AC/harmonic AC voltage at higher voltages. The tensile and flexural strength of the material reduces with thermal aging of OIP material, irrespective of concentration of DBDS in oil.

Arc prevention anchor clamp

Abstract: A preventing arc hardware comprises an upper pressboard and a lower pressboard which are clasped with each other through a bolt, the matching surface of the upper pressboard and the lower pressboard is provided with puncture teeth, each puncture tooth is rabbetted in the upper pressboard or the lower pressboard to form a split rabbet puncture mechanism. As the puncture teeth and the upper pressboard or the lower pressboard of the utility model are the split rabbet, the puncture teeth can be processed into the ideal shape and size independently without the limitation of casting technique. The utility model with reasonable structure can greatly enhance the puncture ability and puncture an insulating layer made of various materials, and is very sufficient in conductive contact. What is more, the puncture teeth can be independently produced by using materials such as red copper, thus leading to better conductivity performance.

Novel energy-saving heat-preservation composite wall board

Abstract: The utility model relates to a heat-preservation composite wall board which is divided into three layers The upper layer and the lower layer are aluminum alloy sheets, and the middle layer is a straw pressboard Reinforcing ribs are arranged in the middle of the straw pressboard and made of asbestos fibers, and are shaped like a Chinese character 'tian' The novel energy-saving heat-preservation composite wall board has the advantages of being low in weight, high in strength, good in heat preservation effect, capable of insulating noise, saving energy and preventing flaming, environmentally friendly and the like