Impulse Creeping Discharge Phenomena on Aerial Insulated Wire under Dry and Wet Conditions

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SUMMARYIn high-voltage aerial distribution systems, creeping discharges progress along the cable surface from the free end of the binding wire when overvoltages caused by a lightning surge have invaded the central line of an insulated cable. Consequently, various accidents such as punchthrough breakdown, melting, or snapping of a cable, often occur at these systems. In our previous studies, it has been clarified that the lengths and aspects of creeping discharges under a 1.2/50 µs impulse voltage condition can be markedly affected by changes in the electric field strength on the cable surface. However, lightning impulse surges which may invade the central line of a cable have various wave front durations. This will further complicate creeping discharge phenomena due to lightning.In this paper, we report the influence of the wave front duration on both the lengths and the aspects of the creeping discharges which progress on the cable on application of lightning impulse voltages. It has been shown that the behavior of negative creeping discharges reveals pronounced changes in response to the duration of the wave front of the applied voltage.

Section: Relationship Between Peak Value Of Applied Impulse Voltage Asupporting

confidence: 67%

Section: (Ii) Negative Creeping Dischargesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The influence of wave front duration of impulse voltage on creeping discharges along aerial insulated wire

Nishi¹,

Hanaoka²,

Takata³

et al. 2004

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“…There are some reports on such linear discharges [2][3][4][5], but their detailed properties are still not fully understood. In the past, we have measured the properties of creeping streamers over wire surfaces initiating from the free ends of the binding wire just after the flashover of the post insulator surface, in order to contribute to countermea-sures against creeping events in aerial distribution systems [6][7][8][9][10]. Creeping discharge phenomena on the wire surface due to actual lightning could be reproduced in the laboratory by applying to the central line of the cable impulse voltages that simulated inductive lightning surges after grounding of the binding wire.…”

Section: Introductionmentioning

confidence: 99%

“…Creeping discharge phenomena on the wire surface due to actual lightning could be reproduced in the laboratory by applying to the central line of the cable impulse voltages that simulated inductive lightning surges after grounding of the binding wire. In our previous papers [7][8][9], a standard lightning impulse voltage was used to simulate an inductive lightning surge. It has been reported that an inductive lightning surge that penetrates to the central line causes an increase of the central line potential, so that the electric fields on the cable surface are altered and a significant negative creeping discharge is included.…”

Section: Introductionmentioning

confidence: 99%

Characteristics of creeping discharge along aerial insulated wire under impulse voltages with various wave front durations

Nishi

Hanaoka

Takata

et al. 2006

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SUMMARYWhen lightning occurs in the neighborhood of outdoor high-voltage distribution lines, creeping discharges propagate along the wire surface from the binding wire tip just after insulator flashover. These discharges give rise to various faults on distribution lines, for instance, disconnection and melting of wire, punch-through breakdown, and so on. We must clarify the creeping discharge characteristics associated with various inductive lightning surges from the viewpoint of safety in high-voltage distribution systems. In our previous paper, it was reported that the lengths and aspects of the negative creeping discharges were influenced by the wave front durations of impulse voltages applied to the central line with a grounded binding wire. The present study was performed to obtain more information on such creeping discharges. This paper describes the distinctive characteristics of a creeping discharge along the insulated wire surface when impulse voltages with various wave front durations are applied to the binding wire.

Development of a positive creeping discharge along an aerial insulated wire

Nishi

Hanaoka

Takata

2010

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SUMMARYIn high-voltage aerial distribution systems, the insulated cables are supported by the binding wire with the post insulator at the utility pole. When a lightning strike occurs in the neighborhood of the insulated cable in an aerial power distribution system, inductive lightning surges invade the central line of the cable. Then, creeping discharges develop along the cable surface from the binding wire tip at the same time as flashover of the post insulator at a supporting point of the cable. If the cable insulator has weak points such as pinholes, a malfunction near the cable supporting point may occur, with melting of the wire due to punch-through breakdown. To prevent such accidents, it is important to clarify the mechanism of the creeping discharge along the insulated cable caused by the lightning strike. The polarity of creeping discharges depends on the polarity of the inductive lightning surges, and the extension length and aspect of the discharge differ greatly depending on the discharge polarity. The development of these creeping discharges is attributed to complicated behavior of the positive and negative electric charges.In the present study, we examined in detail the development of a positive creeping discharge along a wire surface by using a high-speed image converter camera. This paper describes the mechanism of development of a positive creeping discharge based on the experimental results.