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Editorial - Fiftieth Anniversary of TDEI
No full textHaving worked for 25 years as a volunteer for the IEEE Dielectrics and Electrical Insulation Society (DEIS), recently as the Chair of the Publication Committee of the society, I witnessed and personally contributed to some important stages of the historic development of the Transactions on Dielectrics and Electrical Insulation (TDEI). Details of this development were described in the earlier published editorials by Reuben Hackam, Frank Hegeler and Greg Stone and each of them emphasizing the rapid expansion of the number of papers published in the TDEI. Today, close to the edge of my professional carrier as an academic teacher and researcher and based on experiences arising from my personal involvement to in this development as an author, a reviewer as well as a senior associated editor and a guest editor of four special issues of TDEI on Outdoor Insulation and Condition monitoring and Diagnostics, I feel able to deliberate on the reasons for this success story
Insulating materials for next generations of HVAC and HVDC cables
No full text– Scientific co-operations between researchers in the areas of polymer chemists and high voltage engineering concentrate nowadays on development of new insulating materials for HVAC and HVDC cable insulation systems. This contribution presents results of such activities from Sweden, which aim at delivering new material concepts based on polyethylene compounds with added nano-fillers and voltage stabilizers for securing increased resistance to degradation by electrical treeing and reduced electrical conductivity. Several promising stabilizers and nano-fillers have been tested and characterized for the desired impact on the electrical performance
Outdoor Polymeric Insulators: Role of Corona in Performance of Silicone Rubber Housings
No full textIn the struggle to accept outdoor polymeric insulators as alternatives to the traditionally used porcelain and glass insulators, researchers and engineers have tested numerous ideas. Insulator housings made of silicone rubber (SIR) currently dominate the component design, thanks to their hydrophobic surface properties with excellent long-term durability. Despite of five decades of lasting development, some issues related to the performance of this material in various working conditions still remain to be resolved, including an understanding of the impact of corona discharges on the material deterioration as well as on insulator durability although these are extensively studied questions. The impact on insulator performance of high voltage direct current stress especially needs elucidation.An overview on present use of SIR composite insulators is first provided in this paper. Thereafter the results of recent investigations on the mechanism of corona damage are summarized with an emphasis on the differences between the effects of alternating (AC) and direct current (DC) stresses, demonstrating by evaluating the electrical, mechanical and structural characteristics of SIR-based materials, that the damage is less severe under a DC stress. The effect is attributed to reduction in corona intensity in the vicinity of the material surface by stored electric charge. The same charge has however a positive or negative impact on the insulator voltage withstand under impulse conditions, depending on their polarity
Frequency Response of Oil Impregnated Pressboard Samples for Estimating Moisture in Transformer Insulation
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