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Papailiou K.O.,Pfisterer Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

In contrast to composite long rods, composite post insulators are subjected mainly to loads which act perpendicular to the longitudinal axis of the insulator and thus produce bending stresses over the cross-section of the insulator. As a result of this bending load, composite post insulators use FRP rods of substantially greater diameter compared to composite long rods. Typical applications of composite post insulators include distribution insulators, vertical and horizontal line posts, busbar support insulators and railway catenary insulators. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,PFISTERER Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

Partial discharges on the surface of a composite insulator, known as surface partial discharges, are particularly significant because their energy input resulting from an impact and/or heat may damage the solid insulating materials. Whereas air molecules can regenerate themselves, damage to the solid surface is usually permanent and leads to cumulative damage (surface ageing), which may cause the insulation system to fail (fracture, flashover, etc.). Since the term "corona" has been retained in the context of overhead transmission lines, it will also be used here. By the application of some simple mostly empirical rules, it is possible to prevent the occurrence of corona discharges on composite insulator string or sets. Current standards for conventional insulator sets do not differentiate between conventional and composite insulators and are applicable insofar as the occurrence of a continuous corona at hardware components or at the insulator end fitting can be tested directly. The phenomenon of water droplet corona, which depends on numerous factors, should be given special consideration in the case of hydrophobic composite insulators. The composite insulator design (i.e. the material chosen, the stability of the sealing system, etc.) and the stresses that occurs at the service location can play a significant role here. The threshold value 4.5 kV/cm is defined as empirical value and can be regarded as a conservative recommendation, especially in view of the current trend whereby cost pressures are resulting in further developments with a lower fault tolerance. High-grade insulating materials ensure safe operation even when the threshold value for water droplet corona is exceeded. However, this does not apply to insulator sets that are subjected to a continuous corona discharge. Even if acid-resistant (E-CR) glass is used in this scenario, there may be some cumulative damage, which will ultimately cause the composite insulator to fail. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,PFISTERER Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

Composite hollow core insulators (referred to hereinafter as HCI for short) are used primarily as housings for various high-voltage equipment and apparatus. Owing to their conditions for use, they primarily have to withstand bending and compression loads and since a large number of the electrical equipment are gas insulated (with SF6 and SF6 gas mixtures), they are also subject to internal pressure. Today, if the user so desires, it is possible to design complete substations in silicone composite technology. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,Hellbuhlstrasse 37 | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

Line compaction is primarily based on the principle of minimising interphase spacing. As a result of this, and also since the interphase spacings are somewhat smaller than those encountered in the case of normal overhead transmission lines, there is greater risk of interphase flashover with a compact design when two conductors are moved close to one another, for example as a result of wind, ice shedding or short circuit; this may lead to an interruption in service. Interphase spacers (IPS) are used to avoid this. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,Pfisterer Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

High-voltage insulators are of key importance for the operational safety and operating efficiency of transmission systems of electrical power, and it is therefore of no surprise that these components must meet particularly high demands in terms of reliability. In recent years composite insulators have gained great importance in recent years in the field of insulation technology for medium and high-voltage overhead transmission lines and substations. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,Pfisterer Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

This chapter deals with various aspects of standards and tests for composite insulators. The first part lists important IEC standards according to which composite insulators are tested and designed. Since composite insulator strings share functionally-wise many similarities with conventional-especially long rod-insulators, the relevant standards are also listed here for comparative purposes. The second part deals with some testing principles. By using the example of the Inclined Plane Test (IEC 60587), which was initially introduced in 1977 as a material test method for evaluating erosion and tracking resistance, it is possible to show that other properties of polymeric insulating materials can be evaluated using this test principle. The third part discusses analytical methods that can be used to identify the polymeric materials used in a composite insulator. This topic, known as "finger-printing", is also part of the work currently being undertaken by the corresponding CIGRE Working Group. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,PFISTERER Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

Composite long rod insulators are primarily used in suspension strings in straight-line supports and as tension strings in anchor towers and dead-end towers. They are also used in the jumpers or portals of outdoor substations. In some cases, composite long rods are used in the guys of wooden poles, and more rarely in the guys of steel towers. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,Pfisterer Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

This chapter is dedicated to the in-lab evaluation of aged, "old" or failed line composite insulators. The term in-lab evaluation is used, because the state of the insulators or the insulator strings/sets is evaluated as off-line diagnosis, which is different to the inspection method of an on-line diagnosis. It describes various methods, philosophies and resources that make it possible to evaluate their technical state and thus estimate the remaining time of use of composite insulators that are the same type as those being tested. The composite insulators to be evaluated are specifically withdrawn from the line in order to obtain representative results for this generation of insulators. Frequently, analyses are also conducted if old composite insulators are available as part of scheduled replacement schemes. If a certain behaviour has already been identified as being critical to operations, it is recommended to evaluate at least ten insulators. If the line route includes various pollution zones or loads that are otherwise different, a sufficient number of each insulator must be inspected representative for the corresponding in situ conditions. When withdrawing insulators from the network, it is important to ensure that the installation conditions are adequately documented and can be clearly assigned. In many cases, the manufacturer of the composite insulators can provide additional data to identify the product (technical state of a particular generation of insulators, production date, material batches, etc.). In critical cases, it is recommended to perform the evaluation in conjunction with the manufacturer and a specialist independent laboratory. The identification of intensive ageing phenomena that effectively signify the end of service life for an insulator can prompt the withdrawal of other insulators of the same type/generation. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,Pfisterer Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

Compact lines are an interesting alternative to conventional overhead transmission lines where way leaves and also the visual impact on the surrounding landscape are of importance. In addition, compact lines offer further advantages, such as higher power transfer and lower EMC load, and all at a cost which is not necessarily greater than that for conventional lines. © Springer-Verlag Berlin Heidelberg 2013.


Papailiou K.O.,PFISTERER Holding AG | Schmuck F.,Ruchligrain 5
Power Systems | Year: 2013

This chapter reports on the latest materials and production processes used in the manufacture of composite insulators. It also looks back at the development of rod materials as well as experiences relating to the in-house manufacture of glass-fibre reinforced semi-finished parts. PFISTERER SEFAG AG has more than thirty years of experience in processing low viscosity silicone rubber (namely room temperature vulcanising (RTV) rubber and, more recently, liquid silicone rubber (LSR) as well as high viscosity solid silicone rubber (namely high temperature vulcanising (HTV) rubber). Given this level of experience and silicone rubber's acknowledged importance as a reliable housing material, this chapter will focus on providing a detailed account of this group of materials. As a result of the close interaction between material formulations, applicable manufacturing processes and operation-relevant properties, the results of key material analyses will also be presented here. © Springer-Verlag Berlin Heidelberg 2013.

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