An Experimental Investigation of Dynamic Welding Mechanism of Contacts Used in Low Current Switching Devices

Xu, Zili; Zheng, Zhe; Ren, Wanbin; Zhou, Zhefeng

doi:10.1109/holm.2018.8611741

Cited by 5 publications

(4 citation statements)

References 10 publications

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“…The contact blow-open process is a complex one, dependent on the pre-open phenomena [25] and on electrodynamic forces [15,22,26,27]. The current thrusts of research are the effects of blow-open contact bounce on contact welding and the phenomena behind it [4,5,13,26]. Studies regarding the influence of electrodynamic forces [15,28] and high current [29,30] do not cover the electrodynamic action of the operating relay coil.…”

Section: Resultsmentioning

confidence: 99%

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Electrodynamic Contact Bounce Induced by Fault Current in Low-Voltage Relays

et al. 2019

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Due to fault currents occurring in electrical installations, high electromagnetic force values may be induced in current paths of low-voltage electromagnetic relays. This force may lead to an electromagnetic bounce that will further result in an electric arc ignition between contacts, and under some circumstances, it will result in contact welding. For the proper exploitation of relays, the threshold value of the maximum current, and thus the electrodynamic force, should be known. This force depends on several factors, including: contact materials, dimensions of relay current paths, relay electromagnetic coil, etc. This paper presents the results of calculations and an experiment on electromagnetic forces, which cover these factors. A static closing force, acting on the contacts, and the fault current were measured. As a result, values of the force and current threshold were obtained, which inform when an electrodynamic bounce may occur. The obtained result may be used in designing contact rivets and relay current paths together with the selection of adequate fault protection devices.

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Section: Resultsmentioning

confidence: 99%

“…Welded contact will make the relay inoperable, which will necessitate its replacement or an exchange of the entire device within which it is incorporated. The electric arc will lead to the degradation of contact surface and may reduce the expected operating time of the relay [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Electrodynamic Contact Bounce Induced by Fault Current in Low-Voltage Relays

et al. 2019

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“…Electrical contact material is a key material for making on-off control and load current appliances in electric power and electrical circuits [1]. On top of good conductivity and thermal conductivity, electrical contact materials should also have a certain strength, hardness, weld resistance, and arc ablation resistance.…”

Section: Introductionmentioning

confidence: 99%

Erosion Behavior of a Cu-Ti3AlC2 Cathode by Multi-Electric Arc

Huang

Feng

et al. 2019

Materials

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A Cu-Ti3AlC2 cathode was eroded by arc discharging at 10 kV. The cross-sectional and horizontal morphologies of the eroded surface were recorded by a field emission scanning electron microscope (FE-SEM). The energy dispersive X-ray spectroscopy (EDS) and Raman spectrometry were carried out to analyze the compositions. The color-eroded surface was obtained by a three-dimensional laser scanning confocal microscope (3D LSCM). After 100 times of arc erosion, the Cu-Ti3AlC2 melted and resolidified. An eroded layer about 10 μm thick was formed, covered with pits, protrusions, and pores. The breakdown current was kept between 37 to 43 A. Under the action of a high temperature arc, Cu-Ti3AlC2 was oxidized to CuO and TiO2, accompanying the evaporation of the Al element.

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“…Particularly, capacitive load is a common switching duty in DC voltage networks [10]. The inrush current, occurred at the moment of contact touching, could increase the welding probability of contacts during making process [11], [12]. Therefore, the degradation process and typical features of silver tin oxide composite material in terms of the electrical endurance tests are always hot topics in this research field.…”

Section: Introductionmentioning

confidence: 99%

Effect of Electrical Load on Contact Welding Failure of Silver Tin Oxide Material Used in DC Electromechanical Relays

Ren

Zheng

et al. 2019

IEEE Access

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In order to clarify the contact welding failure mechanism of DC electromagnetic relay, a series of electrical endurance tests are carried out with the use of silver tin oxide material under resistive and capacitive load conditions. The typical waveforms of contact voltage and contact current during making and breaking resistive load and capacitive load (load capacitance of 1mF, 1.5mF, 2mF and 2.5mF) are obtained by the designed model switch. Further, the variations of sensitive electrical parameters such as bounce energy, contact resistance, static contact force and break arc energy during electrical endurance test are analyzed explicitly. It is found that the variations in sensitive electrical parameters is closely related to the electrical load type. In particular, under the capacitive load conditions, the sharp increase of each sensitive electrical parameter in the end of lifetime prognosticates the dynamic welding failure of silver tin oxide contact material. Finally, with the help of SEM (Scanning Electron Microscope) pictures of failed contacts, the surface erosion features of contact materials are mainly determined by the competition between the cathode arc and the anode arc. And the material transfer and distribution are the root reason for the contact welding failure of DC electromechanical relays.INDEX TERMS Arc erosion, capacitive load, contact welding, resistive load, silver tin oxide material.

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An Experimental Investigation of Dynamic Welding Mechanism of Contacts Used in Low Current Switching Devices

Cited by 5 publications

References 10 publications

Electrodynamic Contact Bounce Induced by Fault Current in Low-Voltage Relays

Electrodynamic Contact Bounce Induced by Fault Current in Low-Voltage Relays

Erosion Behavior of a Cu-Ti3AlC2 Cathode by Multi-Electric Arc

Effect of Electrical Load on Contact Welding Failure of Silver Tin Oxide Material Used in DC Electromechanical Relays

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