Kazuki Komatsu

Bio: Kazuki Komatsu is an academic researcher. The author has contributed to research in topics: Electric arc & Partial discharge. The author has an hindex of 1, co-authored 1 publications receiving 4 citations.

Assessment of Surface Degradation of Silicone Rubber Caused by Partial Discharge

Abstract: This paper reports experimental and analytical results of partial discharge degradation of silicone rubber sheets in accordance with proposed procedures. Considering the actual usage condition of silicone rubber as an insulating material of polymer insulators, an experimental procedure is established to evaluate long-term surface erosion caused only by partial discharge. Silicone rubber is subjected to partial discharge for 8 h using an electrode system with air gap. Voltage application is stopped for subsequent 16 h for recovery of hydrophobicity. The 24 h cycle is repeated 50 or 100 times. Deterioration of sample surface is evaluated in terms of contact angle and surface roughness. It is confirmed the proposed experimental procedure has advantage of no arc discharge occurrence, good repeatability of results, and possible acceleration of erosion. Surface erosion of silicone rubber progresses gradually and finally breakdown of silicone rubber occurs. Alumina trihydrate (ATH), an additive to avoid tracking and erosion by discharge, is not necessarily effective to prevent breakdown caused by partial discharge when localized electric field in air is enhanced by adding ATH. In such a situation, lower permittivity and higher resistance of silicone rubber seem dominant factors to prevent partial discharge breakdown and a careful insulation design should be required.

Design and Experimental Research on Sealing Structure for a Retrievable Packer

Abstract: In order to reduce the failure accidents of conventional packers, a kind of sealing structure of retrievable packers is designed, which can provide reference for optimizing the sealing performance and pressure capacity of packers. And theoretical calculation and experimental research on their sealing performance and pressure capacity are carried out through the finite element analysis on the contact with large deformation based on Abaqus and experimental study. The results show that the upper packer is subjected to greater stress and mainly plays a sealing role in the sealing process. In order to improve the sealing performance of the packer, the height of the upper and lower packer should be preferentially selected about 60 mm, the height of the middle rubber cylinders should be about 50 mm, and the thickness of the packer should be about 21 mm. The newly designed rubber cylinders can meet 150°C. The newly designed rubber cylinders can meet the sealing function and pressure bearing function under the condition of 10,000 Psi and 150°C. The newly designed rubber cylinder can satisfy the function of sealing and pressure-bearing under 140°C and 10,000 Psi. The whole experiment shows that the capacity of bearing pressure and sealing is stable, which can better meet the requirements of field use.

Electrical Insulation: XLPE Versus Conventional Materials

Abstract: The first part of this chapter presents information about the evolution of power cables and their insulation materials as papers, oils, natural and synthetic rubbers, polyethylene, polyvinyl chloride, polypropylene, polytetrafluoroethylene, etc. The second part analyzes comparatively the values of typical properties of these materials, which are important for the operation of insulation, and their changes under the electrical, thermal, mechanical, and environmental stresses. The variations of conductivity and electrical permittivity, loss factors, and dielectric strength under the action of electric field and temperature are described, as well as the accumulation of space charge and tracking, partial discharges, electrical, and water treeing resistance of DC and AC cable insulation. Among the thermal properties, thermal expansion, thermal conductivity, thermal stability, melting effect, and working temperature are analyzed, and among the mechanical ones are the elasticity, elongation at traction, tensile strength, strength, compressibility, and hardness. The chapter continues with the presentation of chemical, microorganisms, termites, rodents, and resistance to radiation and the estimated lifetime of cable insulation. Finally, the conclusions are shown that XLPE has higher values for most of the properties and are recommended in the manufacture of DC and AC power cables.

Special Issue “Selected Papers from the 2018 IEEE International Conference on High Voltage Engineering (ICHVE 2018)”

Abstract: The 2018 IEEE International Conference on High Voltage Engineering and Application (ICHVE 2018) was organized by the National Technical University of Athens, Greece and endorsed by the IEEE Dielectrics and Electrical Insulation Society [...]