The unusual electrical erosion of high tungsten content, tungsten copper contacts switching load current in vacuum

Slade, Paul G.; Li, None Wangfei; Loud, L.D.; Haskins, R.E.

doi:10.1109/holm.2000.889923

Cited by 7 publications

(1 citation statement)

References 9 publications

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“…Strong arcs can easily form and accumulate on the contact surface, affecting the normal operation of the switch. Therefore, the behavior of the arc ablation of the contact materials is a critical property for the operation safety and reliability of high voltage electrical equipments [8] contact materials in order to achieve a better ablation resistance and prolong service life of the switches, those are through low voltage grade to simulate arc ablation or after analyzing to get related failure mechanism, and by changing the contacts' structure design and usage environment to meet the conditions of usage [9][10][11]. In this paper, the contact materials in opening and closing moment arc producing and extinguishing was simulated by different voltage grade.…”

Section: Introductionmentioning

confidence: 99%

Investigation and analysis of arc ablation on WCu electrical contact materials

Chen

Dong

Zhang

et al. 2016

J Mater Sci: Mater Electron

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In this paper, arc ablation behavior of tungstencopper (WCu) alloy contacts was investigated by the measurement of weight-loss, or erosion rate, and microstructures of tungsten-copper alloy contacts were examined by using scanning electron microscopy after electrical breakdown process. Experimental results showed that the arc erosion process started at the tiny sharp edges, then the arc spreaded on the second phases, or copper phase on the surface. Because of electrons/ions bombardment, the rapid evaporation and sputtering of liquid copper droplets were serious. As a result, an even contact surface became rugged, and tungsten skeleton remained because of being less eroded. With the increase of applied breakdown voltage, the ablation of tungsten-copper alloy became more significant. The WCu alloys with a higher content of copper showed more severe erosion rate as compared with that with a higher tungsten content under the same erosion conditions. Furthermore, when the number of breakdown is less, WCu alloys with a high copper content are easier for erosion for the conditions of fewer numbers of breakdowns. Whereas, WCu alloys with a high content of tungsten are easier for ablation for the conditions with many times of arc breakdown.

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Section: Introductionmentioning

confidence: 99%

Investigation and analysis of arc ablation on WCu electrical contact materials

Chen

Dong

Zhang

et al. 2016

J Mater Sci: Mater Electron

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Surface Degradation of Ag/W Circuit Breaker Contacts During Standardized UL Testing

Sun

Kesim

et al. 2015

J. of Materi Eng and Perform

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The near-surface microstructure of Ag/W contacts from 120 V, 30 A commercial circuit breakers in the asmanufactured condition and after standardized UL overload/temperature-rise, endurance, and short-circuit testing have been investigated using a combination of x-ray diffraction, scanning electron microscopy, energy-dispersive x-ray spectroscopy, focused ion beam milling, and transmission electron microscopy. The as-manufactured contacts comprised three constituents: sintered Ag/W composite particles with finegrained Ag and coarse-grained W, coarse-grained pockets of Ag infiltrate, and a nano-crystalline surface Ag layer. There are also WO 3 and Ag 2 O phases at the surface. After UL overload/temperature-rise testing, there is Ag loss giving a porous W-rich layer at the contact surface. In addition to binary oxides, we observe the formation of Ag 2 WO 4 . After UL endurance testing, material is swept across the surface by the breaker action giving a W-rich eroded porous surface on one side and a build-up of mixed oxides on the other. After UL short-circuit testing, a W crust forms due to melting and re-solidification of W and vaporization of Ag, and mid-plane cracks form due to the severe thermal gradients. There is a strong correlation between the observed microstructural features and the contact resistance measurements obtained from these samples.

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