Non-standard Lightning Research Articles

GISの非標準雷インパルス振動波形に対する絶縁特性

GISの非標準雷インパルス振動波形に対する絶縁特性

GISの非標準雷インパルス振動波形に対する絶縁特性

GISの非標準雷インパルス振動波形に対する絶縁特性

Volt-time characteristics of short air gaps under nonstandard lightning voltage waves

[6 SM 421-8 PWRD, T-PWRD January 1997]. The goal of the present study was to perform a series of statistically designed tests on several types of short air gaps under lightning voltages of nonstandard waveshapes. The objective was to compare the critical breakdown voltage levels, V50, and the volt-time characteristics of these short air gaps under lightning voltages of various waveshapes. The results of the critical breakdown voltages were presented previously. The results of the volt-time characteristics are presented in this paper.

Volt-time characteristics of short air gaps under nonstandard lightning voltage waves

The volt-time characteristics of 5-cm long rod-plane and rod-rod air gaps were experimentally determined with five different waveshapes of the applied impulse voltage. The front time of the waves was varied from 25 ns to 10 /spl mu/s, and the time to half value was varied from 0.5 ps to 100 ps. The volt-time characteristics were also checked analytically using the concept of disruptive effect. The parameters for the disruptive effect were experimentally determined.

Review of research on nonstandard lightning voltage waves

Although the impulse insulation level of a power apparatus is specified under the standard 1.2/spl times/50-/spl mu/s voltage wave, the apparatus seldom encounters such a voltage wave in the field. A wealth of knowledge exists on the behavior of air gaps under nonstandard lightning impulse voltages. The objective of the Task Force was to compile a bibliography on the nonstandard lightning impulse voltages and review the present state of research. This paper reviews the present status of research including the behaviour of air gaps under transient voltages, and the generation and measurement of fast-front impulse voltage waveforms. >

The effects of nonstandard lightning voltage waveshapes on the impulse strength of short air gaps

Sphere-sphere, rod-rod and rod-plane air gaps, each 5-cm long, were tested with lightning surges of eight voltage waves of both polarities. The critical breakdown voltage levels of the tested air gaps attained a minimum plateau within a specific range of wavefronts of the lightning surges. Long time delays of breakdown for the fast-front and short time delays for the slow-front waves were observed. These phenomena would significantly affect the insulation coordination of the power apparatus and systems.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Bibliography of research on nonstandard lightning voltage waves

Because of the increasing importance of the effects of the nonstandard lightning voltage waves on power apparatus, the Task Force was formed to (1) compile a bibliography of the research on the nonstandard lightning voltages, and (2) review the previous research. The bibliography and the review dealt with: (1) behavior of air gaps under nonstandard lightning voltages, (2) generation of fast-front voltage waves, and (3) measurement of fast-front voltage waves. The bibliography is presented in this paper. The bibliography contains 207 publications, published by IEEE and by other societies, in English and in other languages.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Flashover characteristics of air gaps under partly chopped waves

Voltage has been applied to two gaps with series resistances. When flashover occurs at one of the gaps, the applied voltage decreases stepwise but not to zero, because of the series resistance. Flashover characteristics with this gap system have been investigated under various conditions. Experimental results are compared with calculated values obtained with a leader development model. Agreement is good, and it is confirmed that the model is applicable to nonstandard lightning discharges. Two-phase flashover voltage for a short-tail wave is also calculated. The calculated voltage is higher than that obtained by the usual method.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

A New Calculation Method of Breakdown Voltage-Time Characteristics of Long Air Gaps

A new calculation method of leader development which considers predischarge currents is proposed. Calculated leader delopment characteristics with this model are compared with photographs of a image converter camera and close agreement is shown. Further, breakdown voltage-time characteristics of rod-plane and rod-rod gaps with standard and non-standard lightning impulses of both positive and negative polarities are calculated and these values agree with experimental results. This new calculation method is applicable to long gaps of several meters.