Application of functionally graded material for solid insulator in gaseous insulation system

Abstract

Functionally graded materials (FGM) have spatial distribution of a material property in order to achieve efficient stress control. An application of the FGM to a solid insulator (spacer) for a gaseous insulation system, like gas insulated switchgear, is expected to improve electric field (Efield) distribution around the spacer.In this paper, we describe the applicability of the FGM spacer to gas insulated power equipment. In the FGM spacer, we gave spatial distribution of dielectric permittivity to control the E-field distribution inside and outside the spacer. This paper includes following key results for the applications of the FGM. Firstly, E-field simulation results when applying the FGM by a finite element method are presented, in which we show the effective reduction of the maximum field strength by applying the FGM. Next, a fabrication technique of the FGM spacer sample with not only step-by-step but also continuous changes of permittivity is presented by use of centrifugal force. Finally, dielectric breakdown tests using FGM samples which are accurately controlled the spatial distribution of permittivity are carried out under lightning impulse voltage applications. The test result indicates the increase of breakdown voltage (BDV). From these results, we verified the applicability and the fabrication technique of FGM spacer for improvement of the dielectric strength in the gaseous insulation system.

Surface Discharge Characteristics Study on the Laminated Solid Insulator in Quasi-Uniform Electric Field with Dry Air

“…The thickness of the top and bottom parts was 0.5 mm, and that of the middle part was 2 mm. A laminated solid insulator used in this experiment was fabricated based on the similar principle of other researchers [8][9][10] that the flashover voltage was raised by controlling permittivity distribution inside insulator. However, these other studies [8][9][10] presented a single new material consisted of three layers with different permittivity distribution.…”

“…This could produce additional cost for researching and manufacturing new materials. In addition, the permittivity of the new material used in these studies [8][9][10] was higher than that of spacer used in the Gas Insulated Switchgears (GIS). Therefore, this paper presented stacking well-known laminated materials whose permittivity range is within that of spacer currently used in the GIS.…”

“…In particular, the surface discharge of the triple junction can be generated more easily when the electric field intensity is higher. Studies [8][9][10] have been conducted to mitigate the triple junction electric field using solid-insulator permittivity or by increasing the flashover voltage. Kato et.…”

Mechanics of non-slipping adhesive contact on a power-law graded elastic half-space

“…Mechanics of functionally graded materials (FGMs) with spatially varying elastic moduli is of significance to many applications in tribology (Enomoto and Yamamoto, 1998;Donnet and Erdemi, 2004), adhesion (Giannakopoulos and Pallot, 2000;Chen et al, 2009b), geology (Holl, 1940;Booker et al, 1985a,b), biomechanics (Pompe et al, 2003;Hedia and Nemat-Alla, 2004), fracture mechanics (Suresh, 2001), thermo-mechanical systems (Pindera et al, 1998;Nemat-Alla, 2003), energy storage/conversion systems (Kambe and Shikata, 2003;Kato et al, 2006) and nanotechnology (Li et al, 2009;Sioh, 2010). In particular, the contact mechanics of FGMs has received considerable attention in the past (Giannakopoulos and Pallot, 2000).…”

Mode-3 spontaneous crack propagation along functionally graded bimaterial interfaces

“…Current applications of functionally graded materials include wear resistant coatings (Schulz et al, 2003;Gasik et al, 2003;Put et al, 2003;Melgarejo et al, 2006), manufacture of microelectromechanical systems MEMS (Witvrouw and Mehta, 2005), sensors (Muller et al, 2003) and biological implants (Pompe et al, 2003;Watari et al, 2004;Zhang et al, 2005). Graded materials have also found applications in electronic components (Wosko et al, 2005;Kato et al, 2006). Similar to the multitude of applications, there are a variety of manufacturing techniques that can produce functionally graded materials.…”