An investigation into major factors in shunt capacitor switching performances by vacuum circuit breakers with copper-chromium contacts

Kamikawaji, T.; Shiori, T.; Funahashi, T.; Satoh, Y.; Kaneko, E.; Ohshima, I.

doi:10.1109/61.248286

Cited by 37 publications

(7 citation statements)

References 6 publications

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“…1-5. Contrast to the CuCr25 p/m materials with lower strength and ductility, it shows major cleavage fracture of Cr-particles and interfacial fracture between Cr and Cu-matrix after tensile or impact tests (see Figs. [6][7][8][9][10].…”

Section: Discussionmentioning

confidence: 99%

“…However, microstructures of materials are the strategic link among processing, quality, properties and performance, thus microstructure control is essential for any processing activity [9]. With the technical progress of VCB meeting the requirements of power delivery engineering, the microstructure have been taken seriously as a predominant factor in R & D of high performance contact materials [10][11][12][13][14][15]. However, the effects of mechanical properties of contact materials on the interruption capacity and contact performance are not considered as deserved though the relationship is not directly interrelated.…”

Section: Introductionmentioning

confidence: 99%

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The Influence of Mechanical Properties of Contact Materials on the Contact Performance

Miao

Zhang

Liu

et al. 2006

2006 International Symposium on Discharges and Electrical Insulation in Vacuum

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Mechanical properties of two sorts of CuCr(75/25) contact materials adopted widely for vacuum interrupters were determined by standard tensile test and impact test, and fracture characteristics of these two materials after tests were analyzed by optical and SEM equipped with EDS. It was shown that the tensile strength, ductility and impact strength of Cu-25Cr alloy contact material by vacuum casting are superior to that of CuCr25 p/m contact material by sintering technique; Fractographs of these contact materials revealed distinct fracture mechanisms, i.e. dimply ductile fracture of Cu-25Cr alloy materials, in contrast with primarily cleavage fracture of Cr-particles and interfacial fracture between Cr and Cu-matrix in CuCr25 p/m materials. The influence of strength, ductility and interfacial bonding strength between Cr/Cu phases on the contact performance of contact materials were discussed.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

The Influence of Mechanical Properties of Contact Materials on the Contact Performance

Miao

Zhang

Liu

et al. 2006

2006 International Symposium on Discharges and Electrical Insulation in Vacuum

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“…During a following opening process, the welding area is ruptured. It could cause serious damages on the welded contact surfaces [10][11][12][13][14][15][16][17][18][19]. The next prestrike process can be influenced by the deterioration of the contact surface condition.…”

Section: Making Processmentioning

confidence: 99%

“…Kamikawaji et al [10] studied the influence of the inrush current on the restrike probability in a vacuum chamber. Dullni et al [11] found that the restrike Manuscript SW inrush : Inrush current source isolation VCB; U AC : Primary voltage of the transformer T Figure 1.…”

Section: Introductionmentioning

confidence: 99%

Capacitive switching of vacuum interrupters and inrush currents

Yang

Geng

Zhang

et al. 2014

IEEE Trans. Dielect. Electr. Insul.

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The objective of this paper is to investigate an impact of the inrush current on the prestrike and restrike characteristics of vacuum interrupters (VIs) during capacitive current switching duty. Eleven 7.2 kV VIs are used. Their contact parameters are contact gap 4 mm and contact material CuCr25 (25%weight of Cr). A series of 80 CO operations are executed for each test VI. The amplitude of inrush current I inrush (3800 Hz) is set to 0 kA, 2 kA, 5 kA and 10 kA, respectively. The switching current is less than 1 A rms. The (1-cosωt) shape of the recovery voltage with a peak of 15 kV is applied to the test VI. The experimental results show that the prestrike and restrike phenomena are significantly influenced by the contact surface conditions damaged by the inrush current. The cumulative probability of the prestrike gap d pre follows a 3parameter Weibull distribution. When I inrush increases from 2 kA to 5 kA, the prestrike gap increases accordingly. The 10% d pre increases from 0.5 mm to 0.7 mm. The 50% d pre increases from 0.7 mm to 1.0 mm. The 90% d pre increases from 1.0 mm to 1.5 mm. The scale in the Weibull distribution, which can describe the scattering of d pre , is 0.2 mm and 0.6 mm in the case of I inrush = 2 kA and I inrush = 5 kA, respectively. It is found that the occurrence frequency of the inrush current interruption increases from 37.9% to 68.3% with the increase of I inrush from 2 kA to 5 kA. Moreover, the inrush current also has an impact on the restrike types, which are classified into three types according to the waveform features. The average restrike probability increases from 4.6% to 17.9% and further to 30.4% with the increase of the inrush current from 0 kA to 2 kA and 5 kA, respectively. In addition, the higher the inrush current, the restrike tends to occur earlier during the recovery voltage period.

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“…For vacuum CB's , the physical processes during the capacitive switching duty have been studied by [5]. They found that the pre-ignition at contact closing and the subsequent inrush current heavily eroded the contacts leading to detached particles.…”

Section: Introductionmentioning

confidence: 99%

Capacitor bank switching with vacuum circuit breakers

Schellekens

2008

2008 China International Conference on Electricity Distribution

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c 0,1 ell .c 0 le, 0,01 0,001 5 1 NSDD or non-sustained disruptive discharge [7] is a disruptive discharge associated with current interruption that does not result in the resumption of power frequency current or, in the case of capacitive current interruption does not result in current in the main load circuit.which appear as NSDDs Breakdown frequencies of typically 3/1000 where found under the experimental conditions studied. The probability of breakdown depends on the dielectric conception or contact stroke of the vacuum interrupter. So for the same voltage rating different designs lead to different probabilities of occurrence of NSDD. Fig. I shows the experimentally found relation between dielectric conception, based on contact gap, and the probability of a NSDD during an operation. It shows that a minimum contact distance of 16 mm is necessary to reduce this probability below 1/500.The overvoltage produced by a NSDD differs notably from the overvoltage produced by a restrike. A restrike can generate an overvoltage of 3 pu. between the terminals of the capacitor bank, whereas a NSDD causes a sudden voltage shift of the neutral capacitor bank voltage, which leaves the voltage across the capacitor unchanged, but creates an overvoltage between 1.5 and 5 pu. on the terminal of capacitor bank to ground and between 2.5 and 6 pu. across the CB terminals. Due to this high overvoltage a second NSDD in the adjacent phases becomes more likely. 10 15 20 Contact Stroke [mm]Fig.1 : Experimentally found dependence between probability of a NSDD and nominal contact stroke of vacuum interrupter.When two NSDDs occur simultaneously, the phenomenon turns into a restrike. Typically, a vacuum CB with a contact gap of about 16 mm has a probability of about 1/500 for producing a NSDD and belongs to the class C2 with proven "very low restrike probability".Abstract: After interruption of a capacitive current sometimes Non Sustained Disruptive Discharges (NSDDs) are observed when using vacuum circuit breakers. According to network calculations, NSDDs generate significant overvoltage on the terminal of the capacitor bank to ground and across the circuit breaker (CB) terminals. In a full scale experiment at 12kV on an 8Mvar capacitor bank artificial NSDDs are produced using a Triggered Vacuum Gap. The over-voltage depends on the momentary voltage difference across the breaker and, hence, varies with the phase angle. The over-voltage on the terminal of the capacitor bank to ground varies from 1.5 to 4.2 pu, and to maximum 5.2 pu. across the CB terminals. The effectiveness of surge arrestors on the limitation of the over-voltages is measured. The over-voltages are limited to 2.2 pu. on the terminals of the capacitor bank to ground and 3.2 pu. across the CB terminals. A single surge arrestor on the neutral point of the capacitor bank yields the same level of protection and, therefore, is a cost effective alternative. An application guide for switchgear and arrestors is presented.

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An investigation into major factors in shunt capacitor switching performances by vacuum circuit breakers with copper-chromium contacts

Cited by 37 publications

References 6 publications

The Influence of Mechanical Properties of Contact Materials on the Contact Performance

The Influence of Mechanical Properties of Contact Materials on the Contact Performance

Capacitive switching of vacuum interrupters and inrush currents

Capacitor bank switching with vacuum circuit breakers

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