Analysis of Last Development Results for High Voltage Circuit-breakers Using New G3 Gas

Among many alternative gases proposed to replace SF6 as insulating gas, g3 (green gas for grid), fluoronitril based component officially introduced at CIGRE 2014, can be now used for insulation projects and new environmental friendly circuit breakers. This gas mixture g3, presents a reduction of the global warming potential by 98% compared to SF6 gas and shows quite good dielectric withstand capability. Many new investigations about thermal and chemical behavior have been done and are precised in this paper. Last switching test campaigns will be presented for 145 kV applications. Simulation tools should be updated to be applicable to these projects. Developments and comparisons with last test results will be analyzed

Recent Trends in Development of High Voltage Circuit Breakers with SF6 Alternative Gases

The available knowledge of state-of-the-art of SF6 alternative gases in switching applications was collected and evaluated in an initiative of the Current Zero Club together with CIGRE. The present contribution summarizes the main results of this activity and will also include the latest trends. The main properties and switching performance of new gases are compared to SF6. The most promising new gases are at the moment perfluoroketones and perfluoronitriles. Due to the high boiling point of these gases, in HV applications mixtures with CO2 are used. For MV insulation perfluoroketones are mixed with air, but also other combinations might be possible. The dielectric and switching performance of the mixtures, with mixing ratios that allow sufficiently low operating temperatures, is reported to be only slightly below SF6. Minor design changes or de-rating of switchgear are therefore necessary. Differences between the gas mixtures are mainly in the boiling point and the GWP

Application du PET semi-cristallin dans le domaine de la haute tension

Depuis de nombreuses années, ALSTOM Grid prend en considération l’impact environnemental des ses appareillages électriques dès leur conception. Parmi les différents aspects environnementaux, l’amélioration de la recyclabilité des produits constitue un sujet de recherche majeur, spécialement lorsque l’on considère l’utilisation de matériaux polymères. Dans le cadre de l’appareillage électrique haute tension, les matériaux thermodurcissables tels que les résines époxydes utilisées traditionnellement dans cette industrie apparaissent être difficiles à recycler. Ainsi, l’une des voies d’amélioration de la recyclabilité de l’appareillage haute tension réside dans le remplacement, lorsque cela est possible, des thermodurcissables par des matériaux thermoplastiques. Dans ce cadre, nous présentons dans ce papier les recherches menées au sein d’ALSTOM Grid dans le but d’étendre la plage d’application d’un matériau thermoplastique semi-cristallin, le polyéthylène téréphtalate (PET) aux produits haute tension. Nous nous focalisons plus particulièrement au cas de l’application du PET en tant qu’isolateur dans les postes sous enveloppes métalliques de 72,5 kV. Dans un premier temps, les caractéristiques techniques nécessaires à l’application du PET dans le domaine de la haute tension sont discutées en considérant les aspects chimiques, mécaniques et électriques ainsi que la durabilité de ce matériau en regard des contraintes en service. Ensuite, les étapes d’homologation matière et de validation de l’isolateur et du poste sous enveloppes métalliques sont présentées

Étude des propriétés diélectriques du PET en vue d‘utilisation comme isolant recyclable pour appareillages haute tension

International audienc

Diagnostics and Accelerated Life Endurance Testing of Polymeric Materials for HVDC Application

The brochure starts with examining the fundamental processes of electrical ageing of polymeric insulation under dc stress. Then, an overview of diagnostic properties is given to probe the effect of these ageing processes and to determine insulation quality. HVDC testing techniques are described focusing on the tests used for HVDC cable systems from the design phase, via prequalification and type testing to routine testing and diagnostic measurements in service. In the last chapter of the brochure, a number of possible future (on-line) testing methods are presented

Diagnostics and accelerated life endurance testing of polymeric materials for hvdc application - Cigr\ue9 - WG D1.23

There is a renewed and growing interest in high voltage direct current (HVDC) transmission and particularly in the use of polymeric materials as insulation in HVDC equipment. However, many polymers show a non-linear behaviour when they are stressed with DC voltages, a phenomenon which is further amplified by the temperature dependence of the resistivity. Space charges may accumulate that can increase the local electric field and may cause premature failure of the insulation. Thus, space charge formation and dynamics play an important role in the ageing of polymers under HVDC. Partial discharges may occur at dc stress as well and they will be influenced by the space charge formation. Evidently, testing and diagnostics of polymeric materials considered for use in HVDC applications need to take into account the above mentioned phenomena. There are however few standards or technical brochures currently available that tackle this topic. Therefore, the main aim of this document is to describe the techniques used for quality control of materials and combinations of materials for HVDC applications in the factory and on-site, from models of insulation systems to full-size equipment and suggest new techniques where they are deemed to be important. The approach taken by the WG is first to examine the fundamental processes of electrical ageing of polymeric insulation under dc stress. Then, an overview of diagnostic properties is given to probe the effect of these ageing processes and to determine insulation quality. In Chapter 3, the document focuses on space charge and, more in particular, on the relation between chemical composition and stability and the presence of space charge. The interaction between space charge and polymer ageing is discussed in detail. Chapter 4 deals with HVDC testing, focusing on the tests used for HVDC cable systems from the design phase, via prequalification and type testing to routine testing and diagnostic measurements in service. Although many measurement techniques are now available, diagnostic tests that can be used online are virtually non-existent. In Chapter 5, stressing the need for further development in this area, a number of possible future testing methods is presented. Finally, some conclusions are drawn in Chapter 6. In Annexes 1 and 2, currently used practices are described for the measurement of space charge on full-size cables, respectively the test conditions used in Japan for the qualification of polymeric materials for HVDC applications