General expression for positive switching impulse strength valid up to extra long air gaps

Gallet, G.; Leroy, G.; Lacey, Robert J.; Krómer, István

doi:10.1109/t-pas.1975.32045

Cited by 66 publications

(15 citation statements)

References 4 publications

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“…Several equations were proposed to formulate the relationship between the critical flashover voltages (CFOs), and the strike distances for SI voltages [1,[17][18][19]. Equation (1) was proposed in [17] to approximate the critical positive flashover voltage for SI voltages under dry test conditions.…”

Section: Switching Impulse Voltage Testsmentioning

confidence: 99%

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Impacts of corona rings on the insulation performance of composite polymer insulator strings

İlhan

Özdemir

Ismailoglu

2015

IEEE Trans. Dielect. Electr. Insul.

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Corona rings can improve the insulation performance of insulator strings because of their electric field grading property or can decrease the insulation performance due to their arc clearance reduction property. The resulting insulation performance of the string which is under the influence of those two conflicting effects depends on the corona ring parameter settings. Therefore, a detailed experimental work is required to determine the insulation performance for different types of test voltages under different ambient conditions. This paper presents the results of experimental studies regarding the effects of corona rings on the insulation performance of 380 kV non-ceramic V-insulator strings. Those effects and flashover routes were determined for lightning impulses, switching impulses and AC voltages. Corona ring diameter, corona tube diameter, and mounting height were selected as the ring design parameters. Experimental studies were performed for the strings including corona rings of different design parameters as well as for the ring free strings. Test results were discussed from discharge development physics point of view and optimal configuration was determined for the strings.

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Section: Switching Impulse Voltage Testsmentioning

confidence: 99%

“…k g is recommended to be 1.20 for the conductor-window electrode system such as vertical and V-string configurations. Another equation was proposed by [18] for SI voltages, but for the critical wave fronts, and for the gap spacing up to 12 m.…”

Section: Switching Impulse Voltage Testsmentioning

confidence: 99%

Impacts of corona rings on the insulation performance of composite polymer insulator strings

İlhan

Özdemir

Ismailoglu

2015

IEEE Trans. Dielect. Electr. Insul.

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“…Then standard SI tests are done with Tp = 250 Ils. Gallet et al introduced later an alternate equation to calculate USOO/o Sl for a critical time to peak with respect to a given gap spacing [7].…”

Section: Gap Factor Conceptmentioning

confidence: 99%

Factors influencing the switching impulse testing in laboratory conditions

Lachman

Janys

Bolech

et al. 2014

2014 ICHVE International Conference on High Voltage Engineering and Application

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The main aim of this paper is to discuss important aspects with respect to the switching impulse voltage testing of insulator sets under laboratory conditions. Those factors include mainly rain parameters, clearances to the ground, laboratory walls and larger grounded objects (like a rain tower).The testing of glass cap&pin "V" single suspension insulator sets with a setup simulating a tower window (center phase) and a setup acc. to lEe 60383-2 (outside phase) were done in different positions and under dry and wet conditions to see differences in their switching impulse dielectric strength. Repeatability of the testing under dry and wet conditions is discussed also.Finally comparison of measured switching impulse flashover voltage values of given setups with values calculated from a gap factor concept is discussed.

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“…This section treats the breakdown characteristics of various long air gap structures for switching impulse by assuming UHV-class equipment. Figure 4 [14] summarizes the past and recent results of breakdown characteristics of a long air gap of rod-plane electrodes, which is a general fundamental model, under dry condition [9][10][11][12][13][14]. This shows the measurement results of the 50% breakdown voltages using switching impulse waveforms of positive polarity, which is severer in terms of insulation, with the Tp and gap length as parameters.…”

Section: Breakdown Characteristics Of Long Air Gap Insulation For Swimentioning

confidence: 99%

“…Firstly for this purpose, the actual records of switching overvoltage waveforms generated in UHV systems in Japan and China are investigated [2][3][4][5][6][7][8]. Secondly, the insulation characteristics of the long air gap [9][10][11][12][13][14][15][16] and the internal insulation, such as SF 6 gas and oil-paper insulation [17][18][19][20][21][22][23][24][25], for switching impulses with a long Tp are investigated. Based on these results, a study is conducted on the switching impulse test waveform suitable for UHV system equipment.…”

Section: Introductionmentioning

confidence: 99%

Study on switching impulse test waveform for UHV-class electric power equipment

Okabe

Ueta

Tsuboi

et al. 2012

IEEE Trans. Dielect. Electr. Insul.

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Ultra high voltage (UHV) systems are increasingly being planned and constructed, hence studies are promoted on the standard for high-voltage test techniques for UHV-class equipment, the scope of which includes the switching impulse voltage test waveform. Influences that must be considered to study this test waveform are those of actual switching overvoltage waveforms generated in the UHV system and applied to equipment and the change in the breakdown characteristics associated with a longer insulation length such as an air gap clearance. In the present paper, to determine the switching impulse test waveform, switching overvoltage waveforms applied to the UHV equipment were initially investigated. As a result, it emerged that the time to peak Tp was long, ranging from 700 μs to 1000 μs, for closing overvoltage which is relatively high switching overvoltage. When other types of overvoltage in the switching surge range were considered, the Tp varied widely from 100 μs to 1000 μs. Subsequently, the insulation characteristics of UHV-class long air gaps for switching impulse waveforms were investigated. It emerged that, for the fundamental model, namely rod-plane electrodes, the Tp of switching impulse waveforms with the lowest breakdown voltage (critical time to peak, Tcr) ranged from 350 μs to 550 μs whereas it shifted to a shorter time of 200 μs to 350 μs when environmental conditions, such as humidity and precipitation, were taken into consideration. For basic structure models assuming actual facilities and real scale structure models, the Tcr ranged from 100 μs to 300 μs. Furthermore, the internal insulation characteristics for switching impulse waveforms, such as SF 6 gas and oil-paper insulation, were also investigated. Consequently, in the case of the internal insulation of equipment such as gas insulated switchgears (GIS) and transformers, the Tp of switching impulse waveforms had a minor influence on the insulation characteristics, even if it varied from 100 μs to 1000 μs. Following comprehensive evaluation of these characteristics, it was concluded that, in the switching impulse test for UHV-class equipment, it is reasonable to apply a waveform of 250/2500 μs, which is the same as that for equipment of 800 kV or less.Index Terms -Switching impulse voltage test, ultra high voltage (UHV), switching overvoltage, time to peak, critical time to peak, external insulation, air gap clearance, internal insulation, SF 6 gas insulation, oil-paper insulation.

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General expression for positive switching impulse strength valid up to extra long air gaps

Cited by 66 publications

References 4 publications

Impacts of corona rings on the insulation performance of composite polymer insulator strings

Impacts of corona rings on the insulation performance of composite polymer insulator strings

Factors influencing the switching impulse testing in laboratory conditions

Study on switching impulse test waveform for UHV-class electric power equipment

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