Insulator (electricity)

About: Insulator (electricity) is a research topic. Over the lifetime, 15941 publications have been published within this topic receiving 108950 citations. The topic is also known as: electrical insulator.

Electric rotating machine with reduced thickness and volume of insulation

Abstract: An the electric rotating machine which is compact and of reduced cost by improving the thermal conductivity of the main insulation in the thickness direction while maintaining the insulation breakdown voltage of the main insulation high. The initial breakdown voltage V in the thickness direction of the main insulator 30 of the stator winding 3 is higher than 20 kV/mm, and the thermal conductivity λ in the thickness direction is within a range of 0.35 to 1 W/m·K, and the product Vλ of the initial breakdown voltage V and the thermal conductivity λ satisfies a relationship of 7≦Vλ≦20 (MWA/m2·K). The amount of resin is within a range of 20 to 50 weight % of the main insulation material.

Simulation of voltage distribution calculation methods over a string of suspension insulators

Abstract: Insulators for overhead lines are considered to be of basic importance to the transmission system, through their ability to insulate the power lines as well as their function in carrying the weight of the line conductor. For higher voltages, a string of suspension insulators is used. The number of insulator units used depends on the voltages of the lines. The voltage is not equally shared between the units in a suspension insulator string. The capacitances between each cap/pin junction and the tower and between the cap and pin of each unit determine the voltage distribution. Calculation of the voltage distribution can be made by different methods. In this study, these calculation methods and a formulation for each method are studied theoretically through computer programs in case of clean-dry condition. String efficiency comparison for each method is presented, and studying the equalizing voltage drops across insulators is also covered.

Pollution Flashover Under Different Contamination Profiles on High Voltage Insulator: Numerical and Experiment Investigation

Abstract: This work aimed to study the influence of contamination profiles and humidity on flashover electrical characteristics of polluted insulators. Firstly, the flashover tests on cap and pin glass insulators under four pollution levels represented by salinity were conducted. Eight artificial contamination profiles based on the solid layer method have been modeled for the selected insulators. The numerical analysis has been used to determine the insulator electrical characteristics such as potential, electric field, and power dissipation under proposed contamination profiles using finite element methods (FEM). Next, the power dissipation has been simulated with consideration of thermal stress propagation in locations with high power. Finally, flashover voltage gradient tests have been conducted under various humidity and contamination profiles. The values of the flashover voltage gradient due to pollution were determined as the percentage of the value of the flashover voltage gradient in the clean condition which was identified as the reference point. The numerical model indicated that the initiation of arc generally occurs at area in which the electric field and power dissipation is maximum. It was also observed from experimental results that the flashover voltage gradient under different contamination profiles has different values depends on the location and dimension of the pollution region.

The Pressure wave Propagation Metod for the Analysis of Insulating Materials: Application to LDPE Used in HV Cables

Abstract: In the field of electrical insulation, polymers are progressively replacing formerly used materials. When such an insulator is subjected to a voltage gradient, an internal space charge and a polarization develop, eventually reducing the apparent electrical strength of the material. We have applied the pressure wave propagation (PWP) method to the study of HV insulators, such as low density polyethylene (LDPE) used for HV cables. The spatial charge distribution is successively measured in samples subjected to various processes. The influence of additives in the development of a space charge under electric stress is directly shown. We have also observed that the nature of the electrode-iinsulator interface strongly affects the charge distribution throughout the insulator, and that charge injection from these interfaces occurs at much lower applied voltage gradients than previously assumed. The evolution in time of the charge distribution in samples submitted to voltage gradients, at 20 and 700C, is studied. These results show that an equilibrium is reached, from which the life expectancy of materials and cables can be evaluated.