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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.,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.

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