Search

Nanotechnology is rapidly growing as a new technology alternative to create advance materials with unique characteristics and performance for different applications in several industrial sectors. In recent years, many nanotechnology-based products have appeared in our everyday life. On the other hand, industries have also considered nano-concepts to produce high-added value products with superior capacity, reliability and efficiency. Electric insulators are components with high importance in the electricity network system; reliability and high performance are essential characteristics demanded by actual markets. Recent studies have demonstrated the technical feasibility of innovative nano-concepts to improve the final properties of these electrical components. This paper reviews the state-of-the-art of nanotechnology applications for outdoor insulators. Nano-concepts for ceramic insulators are summarized and reported with the aim to provide an overview of applications and opportunities for electric industry. In addition, the future trends and challenges for this field are also considered in this work. [ABSTRACT FROM AUTHOR]

Abstract: Soda-lime glass as a substituent for the feldspar was used to prepare high-tension electrical porcelain by standard chemical solid reaction technique. The effect of glass substitution and sintering temperature on the physical properties, microstructure, hardness, modulus of rupture, flexural strength and Dielectric breakdown strength were examined. Zero water absorption (WA %) and apparent porosity (AP %) were achieved for the samples with glass content >15wt.% sintered at 1100°C. The apparent density was found to increase with sintering temperature. The Vicker’s micro-hardness increased with both glass addition and sintering temperature. Both of the modulus of rupture (MOR) and flexural strength (σf ) had maxima values at 15wt.% glass addition. The structure and morphology were characterized by X-ray diffraction and scanning electron microscope (SEM). It showed the formation of mullite needles at sintering temperature of 1100°C, which enhanced the mechanical and electrical properties of the porcelain. The dielectric breakdown strength increased with sintering temperature and glass addition. The highest dielectric strength was found at 10wt.% of glass addition depending on the Na2O and Fe2O3 content. [Copyright &y& Elsevier]

Differences in the amount of pollution on the top and bottom surfaces of an insulator have a great influence on the dc pollution flashover voltage. Up to now, many investigations have been carried out on non-uniform pollution flashover performance of porcelain and glass insulators, but very few on composite insulators. In this paper the influence of non-uniform pollution distribution on dc composite insulators on their flashover performance was analyzed, and a correction formula for the non-uniform pollution flashover voltage was proposed, based on artificial pollution tests carried out on short samples of a composite insulator intended for ±800kV UHVDC. The test results showed that, when the ratio (T/B) of the salt deposit density (SDD) on the top surface to that on the bottom surface is between 1/1 and 1/10, the value of the characteristic exponent a indicating the effect of SDD on the flashover voltage ranges from 0.22 to 0.255. The value of a is nearly independent of T/B. However, the flashover voltage U50 decreases with the increase in T/B. The correction formula indicating the influence of non-uniform pollution distribution on the flashover voltage could be expressed as K=1 - b×log(T/B). For the tested composite insulators, the factor b was 0.141 to 0.156, which is smaller than that of porcelain or glass insulator. That is to say, the influence of T/B on the flashover voltage of the composite insulator is weaker than those on the porcelain and glass insulators. [ABSTRACT FROM AUTHOR]

Long rod insulators made of porcelain and disc type insulators made of porcelain or glass are the main types of HV insulators used since more than 60 years in overhead transmission and distribution lines and also will be the dominating products in the future. Historically based, there exists much published work on the electrical pollution performance of disc (cap and pin) type HV insulators. Only little knowledge exists about the good service pollution performance of the long rod type insulators. This paper compares the test results obtained from artificial pollution tests according to IEC 61245 with both types of HV insulators under same test conditions. The tests were performed with dc voltage at the FGH (Forschungsgemeinschaft für Elektrische Anlagen), an independent German High Voltage test laboratory. It is well known that the sensitivity of insulator strings to pollution effects is much higher at dc than at ac (50 Hz power frequency) voltage. The test results show an equivalent pollution performance of long rod and disc (cap and pin) type insulators under the same pollution conditions and the same electrical stresses. [ABSTRACT FROM AUTHOR]

This paper presents the study results conducted on the critical flashover (CFO) voltages of the fiberglass distribution line pole and its combination with polymer and porcelain insulators. Special attention was made to evaluate the added CFO voltages by the fiberglass pole to the insulators when pole served as a second component in the distribution line structure. A discussion of the results follows the data obtained. [ABSTRACT FROM PUBLISHER]