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20 kV distribution networks with all its components, such as transformers, switches, cables etc., have existed and been operating safely for many decades. From an economic point of view, it would be convenient to replace the transformer-motor combination by just a single 20 kV asynchronous motor, even if the motor itself were more expensive. The cost of a transformer, facilities and maintenance gained in this way would easily cover the extra costs of a motor. Efficiency consideratkins also make elimination of the step-down transformer desirable. Furthermore, modern technological advances make the production of 20 kV asynchronous motors possible, which is proved by the existence of 32 kV generators. The main problem lies in overcoming the differences between the construction of the aforementioned network equipment and the high-voltage asynchronous motor. This paper analyzes the weak points in the insulation system of an asynchronous motor, and proposes improvements allowing motor supply voltage to be increased to 20 kV. [ABSTRACT FROM AUTHOR]

This paper investigates, through theory and experiment, the applicability of the results obtained in laboratory tests of relatively short duration performed on model structures, as a part of the process of designing high-voltage equipment intended for lasting exploitation. Possibilities and limititions of applying these results to practical structures are examined using the methods of mathematical statistics. Special attention is devoted to the influence of electrode surface enlargement and pulse load (overvoltage) prolongation on the statistical behaviour of the pulse breakdown voltage random variable, expressed in the form of the enlargement law. In the theoretical part of the paper, the general four-dimensional (space-time) enlargement law is derived, along with its simplified three-dimensional (surface-time) variant. In the part of the paper related to the experiment, performed with the aim of testing the applicabililty of the derived surface-time enlargement law to SF6 gas-insulated two-electrode systems, a description of the experimental equipment and procedure is provided, along with the details of measurement data processing. Comparison of experimental results with those predicted by the surface-time enlargement law proved its validity for a two-electrode configuration with a homogenous and radial electric field, insulated by SF6 gas under pressure (with gas pressure as a parameter). [ABSTRACT FROM AUTHOR]

This paper presents an original method to measure ultrafast voltage transient responses and electric field distribution in liquid dielectrics. The capacitive probe is employed to record the fast voltage transient responses. The electric field is reconstructed with multiangular laser scanning of the space between electrodes and a modified arithmetic reconstruction technique. The finite-difference method (FDM) is used to compare and verify experimental results for symmetrical and asymmetrical electrode configurations. Numerical verification confirmed that the experimental results are accurate enough to be used in the design of oil-immersed dielectric systems. [ABSTRACT FROM AUTHOR]

This paper investigates electrical breakdown of interconductor insulation, which presents an obstacle to the increase of the rated voltage of electrical machines as a means to improve efficiency of electrical energy exploitation. We have investigated a large number of samples searching for weak points in interconductor insulation along the coil of a high voltage asynchronous machine. The experiments were performed on lacquer-glass-glass-lacquer conductor insulation. Location of weak points and breakdown voltage levels have been determined. [ABSTRACT FROM AUTHOR]

This paper presents measurement results for the random variable "vacuum breakdown voltage", obtained by the application of pulse, dc, and ac voltage. Parameters varied during the measurements were: 1) vacuum pressure and 2) inter-electrode gap width. The measurements were performed under strictly controlled laboratory conditions. Conclusions about the influence that the variable parameters in the experiment exert on the parameters of theoretical statistical distributions have been drawn, based on the statistical analysis of the obtained experimental results. The obtained results have been explained by the mechanisms constituting the process of electrical breakdown in vacuum. [ABSTRACT FROM AUTHOR]

This paper presents the derivation of the three dimensional scaling law for liquid insulators. The case of the parallel plate capacitor geometry was investigated, and it was assumed that the "breakdown voltage" random variable follows Weibull distribution. The deduced scaling law was experimentally verified for fresh and used mineral transformer oil. Good agreement of the obtained results with theoretical expectations confirms validity and applicability of the three dimensional scaling law in the investigated case. Results obtained in this paper indicate that application of the scaling law is more convenient in the case of oil insulators compared to other insulator types, due to mutual independence of discharge processes. [ABSTRACT FROM AUTHOR]

The application of MOSFETs as detectors or device components in pulse power technique requires an investigation of their characteristics in radiation fields. Computing possibilities of the renowned programs FOTELP and PENELOPE for determining the energy deposited in MOSFET structure and dose distribution within microscopic dimensions of the dosimeter sensitive volume were presented in this paper. Based on the obtained results, qualitative conclusions were drawn about the values of energy deposited in different material zones having various dimensions. The difference between the two codes used for calculations in materials physics and semiconductor technics, basically originates from the different physical models for numerical simulation of photon, positron, and electron transport through various materials. [ABSTRACT FROM AUTHOR]