Władysław Opydo

Analysis of acoustic emission signals accompanying the process of electrical treeing of epoxy resins

The paper presents results of research of electrical treeing of solid dielectrics with the method of acoustic emission (AE). The study was performed on epoxy resins samples at an alternating voltage of 50 Hz. The samples were of cuboidal shape of the dimensions (25×10×4)mm. One of the cuboid sample walls of the dimensions (25×4)mm was covered with a conducting paint. Into the opposite wall a surgical needle of T-25 type was melted into. The distance between the electrodes (the needle and the wall covered with a conducting paint) was in the range 0.5-2.0mm. It was found that AE signals are generated during electrical treeing of epoxy resins. Registered AE signals were denoised with wavelet transformation method and then there were analyzed. Values of chosen parameters increased when the process begins. There are also some dominant frequencies ranges connected with the treeing.

Electric strength of vacuum systems with Co-Mo alloy coated Cu electrodes

The paper presents the results of investigations of the electric strength at 50 Hz AC voltage of vacuum insulation systems that were not subjected to conditioning. The experiments have shown that a Co-Mo alloy coating electrolytically deposited on the surface of copper electrodes causes, at the pressure 2 mPa, >25% increase of electric strength of unconditioned vacuum insulation systems. This breakdown strength decreases with increasing gap spacing between the electrodes, and amounts /spl sim/17 kV/mm for systems with Cu electrodes at the electrode gap of 1 mm, and /spl sim/9 kV/mm at a gap of 6 mm. Plane electrodes with rounded-off edges of Rogowskis profile were used in the investigations. The electrodes with 50 mm diameter, were made of OFHC Cu. The paper shows the influence of the value of pressure from /spl sim/1 mPa to 1 Pa and at constant pressure of /spl sim/1 mPa, the length of vacuum gap, and the presence of a Co-Mo alloy layer coating the electrodes. >

Optimization of insulators for vacuum insulated devices

The paper presents optimizing high voltage stand-off insulators for vacuum devices which work at alternating voltage at power-line frequency. In order to achieve the maximum surface electrical strength of the insulator, optimizing calculations were made concerning both the shape of the side surface of insulating material and the shape of electrodes controlling distribution of the electric field (insulators ferrules). The article presents results of optimization and experimental insulator research.

Influence of cobalt-molybdenum-alloy coating on the surface of copper electrodes upon electric strength of unconditioned vacuum-insulation systems

The paper presents the results of investigations of electric strength at AC voltage (50 Hz) of vacuum insulation systems which were not subject to conditioning. Plane electrodes with rounded-off edges of Rogowskis profile were used in the investigations. The electrodes, having diameters of 50 mm, were made of OFHC copper. The paper shows the influence of fundamental factors defining the conditions of a vacuum insulation system on its electric strength, such as: the value of pressure (within the scope of approximately 1 mPa - 1 Pa) and at constant value pressure approximately 1 mPa, the length of vacuum gap, and the pressure of cobalt-molybdenum alloy layer coating the surfaces of the electrodes.