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This article presents the results of research on the thermal state of vacuum switch contacts during the conduction of short-circuit currents. This state is directly related to the value of the flowing current and the operating conditions of the switch. These conditions are mildest in the case of the conduction of operating currents through closed contacts. The situation worsens significantly when short-circuit currents are conducted, and the greatest destructive effects occur during commutation processes. Exceeding a certain level of contact destruction usually leads to the loss of the switching capacity of the switch. In vacuum switches, tracking the thermal state of the contacts is particularly difficult due to the inaccessibility of transducers or measurement sensors inside the chamber. In such a case, simulation studies verified by experimental results are important. This paper presents the results of such studies, directed at their practical implementation in the design and operation of vacuum switches. Simulation studies were conducted to analyze the thermal processes occurring in the contacts of vacuum switches during the conduction of short-circuit currents. Special attention was paid to the influence of contact parameters on the thermal processes occurring during the conduction of short-circuit currents. In addition to simulations, experimental studies were carried out to verify the simulation results. Ultimately, the research results presented are intended to provide practical knowledge of the design and operation of vacuum switches, particularly with regard to the contact heating processes during the conduction of short-circuit currents. [ABSTRACT FROM AUTHOR]

Micro-Electromechanical-Relay (MER) has widely achieved application in the field of engineering thanks to the excellent features and ever-growing interest in microelectronic products. However, the adhesion phenomenon between gold-sputtered contact pairs in MER usually brings about operating failure of normally closed contacts limiting the reliability level of MER. In this paper, various contact combinations between electrical contact pairs are assembled to simulate real contact conditions, and associated failure type is built by taking advantage of mechanical adhesion theory to reveal failure mechanism about cold adhesion. It is found that the adhesion force is correlated closely with the surface roughness of contact pairs. The specific contact combination is a significant effective strategy to reduce the adhesion failure between electrical contacts. [ABSTRACT FROM AUTHOR]

The contact finger electrical connection structure is a crucial component of high voltage bushings, and its safety and reliability directly impact the operational stability of the bushing. To investigate electrical contact performance of the contact finger under eccentric conditions, a three‐dimensional electrical, thermal, and force multi‐physics coupling calculation model was established. Additionally, a test platform was constructed to measure electrical contact characteristics of the contact finger. The contact characteristics of the contact finger when the male head was axially deflected and radially offset compared to the female head were obtained. The research findings indicate when the male head deflects axially, the contact force changes of the contact finger blades on both sides are opposite. Moreover, as the axial deflection angle of the male head increases, the resistance of the electrical connection structure shows a rising‐slow decreasing‐fluctuating trend. The resistance is highest at 3°, with a resistance increase rate of 7.35%. Furthermore, the resistance of the electrical connection structure varies with the radial offset of the male head, following a power function. Contact failure occurs when the radial offset is 1.31 mm, and the resistance increase rate reaches 24.9% at a radial offset of 1.58 mm. [ABSTRACT FROM AUTHOR]

Abstract The contact finger electrical connection structure is a crucial component of high voltage bushings, and its safety and reliability directly impact the operational stability of the bushing. To investigate electrical contact performance of the contact finger under eccentric conditions, a three‐dimensional electrical, thermal, and force multi‐physics coupling calculation model was established. Additionally, a test platform was constructed to measure electrical contact characteristics of the contact finger. The contact characteristics of the contact finger when the male head was axially deflected and radially offset compared to the female head were obtained. The research findings indicate when the male head deflects axially, the contact force changes of the contact finger blades on both sides are opposite. Moreover, as the axial deflection angle of the male head increases, the resistance of the electrical connection structure shows a rising‐slow decreasing‐fluctuating trend. The resistance is highest at 3°, with a resistance increase rate of 7.35%. Furthermore, the resistance of the electrical connection structure varies with the radial offset of the male head, following a power function. Contact failure occurs when the radial offset is 1.31 mm, and the resistance increase rate reaches 24.9% at a radial offset of 1.58 mm.

Graphene with an atomically thin structure is considered to be a highly sensitive transducer capable of converting diverse external stimuli into measurable electrical signals. The generated signals, such as current and resistance, can be extracted through electrical contact to graphene. Conventional methods for contact formation are usually based on physical deposition of conductive materials on the target graphene. Here, we propose a method for in situ chemical synthesis of electrical contacts to graphene as an alternative approach that complements conventional physical methods. CO2 laser irradiation on a polyimide film with monolayer graphene on top can convert the polyimide surface to conductive electrodes of laser-induced graphene (LIG) that electrically connect to the existing graphene channel. Laser-scribing conditions, such as the power and scan rate, can modulate the contact resistance of the LIG–graphene junction. Various arbitrary shapes of in situ LIG contacts can be scribed to the direct writing ability of the laser. The proposed in situ LIG contact method can be extended to other carbon nanomaterials, such as carbon nanotubes and PEDOT:PSS. As a proof of concept of the in situ LIG contacts to graphene for electronic device applications, graphene field-effect transistors were demonstrated on a graphene-supported polyimide substrate with LIG–graphene junctions as source/drain electrodes. Our approach will pave the way for the simple and low-cost fabrication of versatile graphene electronic devices by utilizing the existing LIG technology specialized for energy devices and sensors. [ABSTRACT FROM AUTHOR]

Microscope projection photolithography (MPP) offers a versatile method of prototyping microscale devices. The benefits of MPP include the ability to create features at a variety of dimensions, the ability to work outside of a clean room, and the ability to use robotic microscope stage controls to adjust the positions of features easily and accurately. This makes MPP a precise, yet flexible technique ideal for manufacturing contact pads that can be used to investigate the properties of individual nanowires. An enormous breadth of research has been dedicated to the synthesis and characterization of nanowires. The properties of individual nanowires can, however, vary greatly between syntheses or within a batch. Characterization of individual nanowires remains an important step in the scale-up of these materials. Their characterization does, however, often require complex and highly sensitive self-assembly techniques to arrange nanowires on substrates with proper placement of electrical contacts. Some work has been done on techniques for the selective characterization of individual nanowires, but those methods rely on using focused electron-beam writing techniques to connect nanowires to pre-existing electrical contacts. The study of nanowires would benefit from a rapid, flexible approach to fabricating contacts for individual nanowires. This study demonstrates a system for fabricating electrical contacts with minimum feature sizes of ∼0.9 μm on individual nanowires (e.g., diameters from <75 to >125 nm) that are positioned randomly on a small substrate (e.g., <1 cm2). Designs for double and quadruple contact pads have been shown to enable the effective measurement of the electrical properties of individual nanowires. The techniques provided herein can provide a rapid, simple, and customizable method of studying individual nanowires. [ABSTRACT FROM AUTHOR]

Featured Application: The innovative graphene-enhanced CuW composites can be applied to 252~1100 kV high-voltage circuit breakers to improve the breaking capacity of high-voltage circuit breakers. To address the issue of over-standard short-circuit currents in a power system, it is imperative to enhance the comprehensive performance of the electrical contacts, which serve as the lynchpin of circuit breakers, so as to improve the breaking capacity of high-voltage circuit breakers. Graphene, as the most prominent two-dimensional carbon material in recent years, has garnered widespread applications across various fields. In this study, graphene-enhanced CuW composites for high-voltage circuit breaker electrical contacts were prepared innovatively using integrated vacuum infiltration technology. The innovative graphene-enhanced CuW composites significantly improved the mechanical, electrical, and ablation resistance properties, and have been successfully applied in the 252 kV/63 kA high-voltage SF6 circuit breakers, achieving 20 times effective consecutive full-capacity short-circuit current breaking. It provides a new route for the development and application of high-performance CuW electrical contacts. Looking ahead, it is planned to extend their application to higher voltage grade high-voltage circuit breakers. [ABSTRACT FROM AUTHOR]

Abstract Recent discovery of ultrathick MoSi2N4(MoN)n monolayers open up an exciting platform to engineer two‐dimensional (2D) material properties via intercalation architecture. In this study, a series of ultrathick MA2N4(M'N) monolayers (M, M' = Mo, W; A = Si, Ge) is computationally investigated under both homolayer and heterolayer intercalation architectures, in which the same and different species of transition metal nitride inner core sublayer are intercalated by outer passivating nitride sublayers, respectively. The MA2N4(M'N) are stable metallic monolayers with excellent mechanical strength. Intriguingly, the metallic states around Fermi level are localized within the inner core sublayer. Carrier conduction mediated by electronic states around the Fermi level is thus spatially insulated from the external environment by the native outer nitride sublayers, suggesting the potential of MA2N4(M'N) in back‐end‐of‐line metal interconnect applications. N and Si (or Ge) vacancy defects at the outer sublayers create ‘punch through’ states around the Fermi level that bridges the carrier conduction in the inner core sublayer and the outer environment, forming an electrical contact akin to the ‘via' structures of metal interconnects. It is further shown that MoSi2N4(MoN) can serve as a quasi‐Ohmic contact to 2D WSe2. These findings reveal the potential of ultrathick MA2N4(MN) monolayers in interconnect and metal contact applications.

Wireless power transfer (WPT) is now ubiquitous, having penetrated almost every industry within the last 20 years, due to certain desirable attributes explained in this paper. Furthermore, WPT is now in an advanced state whereby it is now technically feasible to apply the methods of WPT to the connector industry and surmount commonplace problems that have plagued the electrical connector industry since the invention of the first electrical connector in 1885. Whereas other common technologies have evolved greatly over the last two centuries with the emergence and development of new primary mechanisms, the primary mechanism used in electrical connectors-the electrical contact-has not changed. The electrical contact is the source of many failure modes, several of which can be eliminated by applying the WPT methodology through a new type of connector called the Non-Metallic Connector (NMC). As a result, connectors can now be made entirely contactless, possessing a hermetically sealed interface that is also shockproof. The NMC concept is applicable to both signal transfer and power transfer. NMCs fall into the categories of both near-zone and far-zone technologies, necessitating thereby the introduction of the $\mu $ WPT in the commonly accepted WPT hierarchy. Appropriate circuit topologies as well as major design challenges are identified for power-transfer NMCs with appropriate methods to overcome those challenges, based on the electrical power handling requirement.

This article presents the results of research on the thermal state of vacuum switch contacts during the conduction of short-circuit currents. This state is directly related to the value of the flowing current and the operating conditions of the switch. These conditions are mildest in the case of the conduction of operating currents through closed contacts. The situation worsens significantly when short-circuit currents are conducted, and the greatest destructive effects occur during commutation processes. Exceeding a certain level of contact destruction usually leads to the loss of the switching capacity of the switch. In vacuum switches, tracking the thermal state of the contacts is particularly difficult due to the inaccessibility of transducers or measurement sensors inside the chamber. In such a case, simulation studies verified by experimental results are important. This paper presents the results of such studies, directed at their practical implementation in the design and operation of vacuum switches. Simulation studies were conducted to analyze the thermal processes occurring in the contacts of vacuum switches during the conduction of short-circuit currents. Special attention was paid to the influence of contact parameters on the thermal processes occurring during the conduction of short-circuit currents. In addition to simulations, experimental studies were carried out to verify the simulation results. Ultimately, the research results presented are intended to provide practical knowledge of the design and operation of vacuum switches, particularly with regard to the contact heating processes during the conduction of short-circuit currents.

To address the issue of over-standard short-circuit currents in a power system, it is imperative to enhance the comprehensive performance of the electrical contacts, which serve as the lynchpin of circuit breakers, so as to improve the breaking capacity of high-voltage circuit breakers. Graphene, as the most prominent two-dimensional carbon material in recent years, has garnered widespread applications across various fields. In this study, graphene-enhanced CuW composites for high-voltage circuit breaker electrical contacts were prepared innovatively using integrated vacuum infiltration technology. The innovative graphene-enhanced CuW composites significantly improved the mechanical, electrical, and ablation resistance properties, and have been successfully applied in the 252 kV/63 kA high-voltage SF6 circuit breakers, achieving 20 times effective consecutive full-capacity short-circuit current breaking. It provides a new route for the development and application of high-performance CuW electrical contacts. Looking ahead, it is planned to extend their application to higher voltage grade high-voltage circuit breakers.

In this work, the wear and melt erosion behavior of tin-plated copper alloy contacts are investigated under fretting at current loads ranging from 0.1 to 12.5 A. Three typical variations in the average values of contact resistance and contact temperature with fretting cycles are recorded and interpreted explicitly. The material melt erosion in the contact interface is observed clearly at currents higher than 5 A due to substantial Joule heat. The increment of contact temperature together with the distortion of transient friction force are considered as the degradation characteristics in the fretting. The produced scars and oxides between the contact interface eventually lead to the electric circuit disconnection. The distinct physical mechanism of contact interface fretting wear and melt erosion at high current loads is presented. [ABSTRACT FROM AUTHOR]