scholarly journals Influence of Single and Multiple Dry Bands on Critical Flashover Voltage of Silicone Rubber Outdoor Insulators: Simulation and Experimental Study

Energies ◽  
2018 ◽  
Vol 11 (6) ◽  
pp. 1335 ◽  
Author(s):  
Arshad ◽  
Muhammad Mughal ◽  
Azam Nekahi ◽  
Mansoor Khan ◽  
Farhana Umer
Keyword(s):  
Experimental Study ◽  
Silicone Rubber ◽  
Flashover Voltage ◽  
Outdoor Insulators ◽  
Dry Bands

scholarly journals A Study of SiR/EPDM Mixtures for Outdoor Insulators

2017 ◽  
Vol 7 (4) ◽  
pp. 1737-1740
Author(s):  
A. Sykaras ◽  
V. Rajini ◽  
M. Danikas ◽  
R. Sarathi
Keyword(s):  
Electric Field ◽  
Silicone Rubber ◽  
Water Droplet ◽  
Uniform Electric Field ◽  
Ethylene Propylene Diene Monomer ◽  
Ethylene Propylene ◽  
Flashover Voltage ◽  
Outdoor Insulators

This paper deals with the flashover voltages on samples of silicone rubber/ethylene propylene diene monomer (SiR/EPDM) mixtures under the influence of a uniform electric field. Five different mixtures of SiR/EPDM were investigated. Various SiR/EPDM mixtures (100% EPDM, 10% SiR + 90% EPDM, 30% SiR + 70% EPDM, 50% SiR + 50% EPDM, 70% SiR + 30% EPDM, 90% SiR + 10% EPDM, 100% SiR) were tested for different water droplet arrangements, different water conductivities, different droplet volumes as well as different droplet positioning w.r.t. the electrodes. The 50% SiR + 50% EPDM mixture proved to be the best mixture regarding the flashover voltage.

scholarly journals Modeling of Dry Band Formation and Arcing Processes on the Polluted Composite Insulator Surface

Energies ◽  
2019 ◽  
Vol 12 (20) ◽  
pp. 3905
Author(s):  
Jiahong He ◽  
Kang He ◽  
Bingtuan Gao
Keyword(s):  
Energy Balance Equation ◽  
Field Calculation ◽  
Composite Insulator ◽  
Band Formation ◽  
Insulator Surface ◽  
Thermal Fields ◽  
Flashover Voltage ◽  
Before And After ◽  
Difference Time ◽  
Dry Bands

This paper modeled the dry band formation and arcing processes on the composite insulator surface to investigate the mechanism of dry band arcing and optimize the insulator geometry. The model calculates the instantaneous electric and thermal fields before and after arc initialization by a generalized finite difference time domain (GFDTD) method. This method improves the field calculation accuracy at a high precision requirement area and reduces the computational complexity at a low precision requirement area. Heat transfer on the insulator surface is evaluated by a thermal energy balance equation to simulate a dry band formation process. Flashover experiments were conducted under contaminated conditions to verify the theoretical model. Both simulation and experiments results show that dry bands were initially formed close to high voltage (HV) and ground electrodes because the electric field and leakage current density around electrode are higher when compared to other locations along the insulator creepage distance. Three geometry factors (creepage factor, shed angle, and alternative shed ratio) were optimized when the insulator creepage distances remained the same. Fifty percent flashover voltage and average duration time from dry band generation moment to flashover were calculated to evaluate the insulator performance under contaminated conditions. This model analyzes the dry band arcing process on the insulator surface and provides detailed information for engineers in composite insulator design.

Silicone rubber tubulization in peripheral sensory nerve reconstruction: An experimental study in rabbits

Microsurgery ◽  
2001 ◽  
Vol 21 (7) ◽  
pp. 306-316 ◽  
Author(s):  
Guda C.M. Heijke ◽  
Pieter J. Klopper ◽  
Bob Baljet ◽  
Ilona B.M. van Doorn
Keyword(s):  
Experimental Study ◽  
Silicone Rubber ◽  
Sensory Nerve ◽  
Nerve Reconstruction ◽  
Peripheral Sensory

scholarly journals Influence of Silicone Rubber Coating on the Characteristics of Surface Streamer Discharge

Polymers ◽  
2021 ◽  
Vol 13 (21) ◽  
pp. 3784
Author(s):  
Xiaobo Meng ◽  
Liming Wang ◽  
Hongwei Mei ◽  
Chuyan Zhang
Keyword(s):  
Silicone Rubber ◽  
Electrical Power ◽  
Electrical Power System ◽  
Streamer Discharge ◽  
Reliable Operation ◽  
Pollution Flashover ◽  
Flashover Voltage ◽  
Streamer Propagation ◽  
Rubber Coating ◽  
Rubber Coatings

A pollution flashover along an insulation surface—a catastrophic accident in electrical power system—threatens the safe and reliable operation of a power grid. Silicone rubber coatings are applied to the surfaces of other insulation materials in order to improve the pollution flashover voltage of the insulation structure. It is generally believed that the hydrophobicity of the silicone rubber coating is key to blocking the physical process of pollution flashover, which prevents the formation of continuously wet pollution areas. However, it is unclear whether silicone rubber coating can suppress the generation of pre-discharges such as corona discharge and streamer discharge. In this research, the influence of silicone rubber coating on the characteristics of surface streamer discharge was researched in-depth. The streamer ‘stability’ propagation fields of the polymer are lower than that of the polymer with silicone rubber coating. The velocities of the streamer propagation along the polymer are higher than those along the polymer with silicone rubber coating. This indicates that the surface properties of the polymer with the silicone rubber coating are less favorable for streamer propagation than those of the polymer.

scholarly journals Development and evaluation of silicone membrane as aerators for membrane bioreactors

2005 ◽  
Author(s):  
◽  
Xolani Proffessor Mbulawa
Keyword(s):  
Mass Transfer ◽  
Experimental Study ◽  
Dissolved Oxygen ◽  
Oxygen Concentration ◽  
Silicone Rubber ◽  
Convective Transport ◽  
Operating Conditions ◽  
Pure Oxygen ◽  
Bulk Liquid ◽  
Dissolved Oxygen Concentration

In bubble-less aeration oxygen diffuses through the membrane in a molecular form and dissolves in the liquid. Oxygen is fed through the lumen side of silicone rubber tube. On the outer surface of the membrane there is a boundary layer that is created by oxygen. This then gets transported to the bulk liquid by convective transport created by water circulation through the pump. The driving force of the convective transport is due to concentration difference between the dissolved oxygen in water and oxygen saturation concentration in water at a particular temperature and pressure. The design of a membrane aerated bioreactor needs an understanding of the factors that govern oxygen mass transfer. It is necessary to know the effects of operating conditions and design configurations. Although various methods of bubble-less aeration have been reported, there still exists a lack of knowledge on the immersed membrane systems. This study is aiming at contributing to the development of an immersed membrane bioreactor using silicone rubber tubular membrane as means of providing oxygen. The secondary objective was to investigate the influence that the operating conditions and module configuration have on the system behaviour. From the experimental study, the characteristic dissolved oxygen -time curve show that there is a saturation limit equivalent to the equilibrium dissolved oxygen concentration, after which there is no increase in dissolved oxygen with time. At ambient conditions the equilibrium dissolved oxygen is approximately 8 mg/L. This is when water is in contact with air at one atmospheric pressure. At the same conditions the equilibrium dissolved oxygen concentration when water is in contact with pure oxygen is approximately 40 mg/L. This is why all the experiments were conducted from 2mg/L dissolved oxygen concentration in water, to enable enough time to reach equilibrium so as to determine mass transfer coefficient. The most important parameters that were investigated to characterise the reactor were, oxygen supply pressure, crossflow velocity, temperature and module orientation. Observations from the experimental study indicated that when the system is controlled by pressure, crossflow does not have a significant effect on mass transfer. When the system is controlled by the convective transport from the membrane surface to the bulk liquid, pressure does not have a significant effect on mass transfer. All four effects that were investigated in the study are discussed.

scholarly journals Effect of mineral oil on flashover voltage of HTV silicone rubber under AC corona ageing: from the view of trap level distribution

2020 ◽  
Vol 14 (23) ◽  
pp. 5498-5504
Author(s):  
Yu Yu ◽  
Ke Wang ◽  
Yan Yang ◽  
Gang Li ◽  
Guangning Wu ◽  
...  
Keyword(s):  
Silicone Rubber ◽  
Mineral Oil ◽  
Trap Level ◽  
Flashover Voltage
Sign in / Sign up

Export Citation Format

Share Document