Estimation of the Size of Voids in Coil Insulation of Rotating Machine

Hirabayashi, Shoji; Shibuya, Y.; Hasegawa, Takeshi; Inuishi, Yoshio

doi:10.1109/tei.1974.299322

Cited by 15 publications

(2 citation statements)

References 3 publications

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“…Discharges within cavities (voids) in solid insulating system [4] have long been associated with gradual degradation and dielectric failure. The correlation between cavity discharge and degradation has been established for rotating machines [5], power cables [6] encapsulated transformers and many other solid dielectric systems so that the correlation between cavity discharge and degradation is now well established. Gas filled cavities can originate in a wide range of solid dielectric systems through many mechanism including differential thermal expansion(composite systems) incomplete impregnation or excessive mechanical stress(fiber reinforced systems) or improper process control (epoxy castings).Cavities can also originate over a lifetime of operation as a result of environmental stresses.…”

Section: Introductionmentioning

confidence: 99%

Estimation of partial discharge inception voltages in the ambient medium of SF<inf>6</inf>

Zuberi

Masood

Husain

et al. 2008

2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century

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In this paper we report a technique for estimating the Partial Discharge (PD) inception voltages in case of discharges occurring at the interface as well as in voids in the ambient medium of Sulphur Hexafluoride gas (SF 6 ). Since occurrence of PD is a phenomenon dependent on upon many factors such as the type of gas in the void, the gas pressure, surface properties of the void, size and shape of the void, dielectric constant of the surrounding medium; these parameters have to be taken into account. The computed values are valid in the pressure range of 0.067 kPa to 101.333 kPa. Computations are accurate to ± 3.5 % in the pt′ range of 0.3 -1200 kPa-cm. These computations are useful in understanding discharges in the insulation system of cables, capacitors, GIS, bushings or epoxy cast equipment which are dried and impregnated at low pressures and may contain gas pockets at sub-atmospheric pressures. These computations are also important and useful for high altitude insulation design and spacecraft insulation.

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Section: Introductionmentioning

confidence: 99%

Estimation of partial discharge inception voltages in the ambient medium of SF<inf>6</inf>

Zuberi

Masood

Husain

et al. 2008

2008 IEEE Power and Energy Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century

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“…This case is also very interesting from an industrial point of view, since even in a small volume of polymeric material a large number of voids may be found. Research carried out about three decades ago was of a rather theoretical nature and showed that it was possible from partial discharge data to obtain the distribution of void size in rotating machine insulation by using a transformation method [15,16]. The aim of the present paper is to simulate the electrical tree growth in solid dielectrics containing voids of arbitrary shape using von Newmann's cellular automata.…”

Section: Introductionmentioning

confidence: 99%

Simulation of electrical tree growth in solid dielectrics containing voids of arbitrary shape

Danikas

Karafyllidis

Thanailakis

et al. 1996

Modelling Simul. Mater. Sci. Eng.

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In this paper the electrical tree growth in solid insulating materials containing voids of arbitrary shape is modelled using von Neumann's cellular automata (CA). The model is based upon the assumption that the electric stress at the end of a conducting tip quite often approaches the dielectric strength of the material and that progressive breakdown may occur by electrical tree formation. Because of tree advancement, the potential distribution within the insulating material changes with time, and it is calculated at each time step. An algorithm, based on this model, for the simulation of electrical tree growth in solid dielectrics containing voids of arbitrary shape has been developed. Simulation results show that voids constitute a danger for solid insulation, because they act as sources of secondary electrical trees. An interaction mechanism between voids within a dielectric is proposed and discussed.

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