Contact Switch Research Articles

Application of Surge Arrester in Limiting Voltage Stress at Direct Current Breaker

Hybrid DC circuit breakers combine mechanical switches with a redirecting current path, typically controlled by power electronic devices, to prevent arcing during switch contact separation. The authors’ past work includes a bipolar hybrid DC circuit breaker that effectively redirects the fault current and returns it to the source. This reduces arcing between the mechanical breaker’s contacts and prevents large voltage overshoots across them. However, the breaker’s performance declines as the upstream line inductance increases, causing overvoltage. This work introduces a modification to the originally proposed hybrid DC breaker to make it suitable to use anywhere along DC grid lines. By using a switch-controlled surge arrester in parallel with the DC breaker, part of the arc energy is dissipated in the surge arrester, preventing an overvoltage across the mechanical switches. Based on the experimental results, the proposed method can effectively interrupt the fault current with minimal arcing and reduce the voltage stress across the mechanical switches. To address practical fault currents, tests at high fault currents (900 A) and voltage levels (500 V) are conducted and compared with simulation models and analytical studies. Furthermore, the application of the breaker for the protection of DC distribution grids is illustrated through simulations, and the procedure for designing the breaker components is explained.

Optimal configuration of acquisition terminals in regional distribution grids considering dynamic observability

Optimizing the configuration of acquisition terminals can maximize the observability and state estimation accuracy of the distribution grid achieving comprehensive perception of the distribution grid. However, the existing optimization configuration methods typically target a single topology structure. For regional distribution grids with dynamic topology changes, it cannot meet the observability requirements of all their topologies. In this regard, this paper proposes an optimal configuration scheme for regional distribution grid acquisition terminals considering dynamic observability. Firstly, the regional distribution grid considering the change of contact switch is modeled. Based on the observation redundancy and state estimation accuracy, the dynamic observability index of regional distribution grid is proposed. Then, a multi-objective optimal configuration model of acquisition terminal is constructed with the objective function of maximizing dynamic observability and minimizing configuration cost. Finally, the effectiveness of the proposed approach is validated with the simulation model.

Analysis of billet temperature non-uniformity in a regenerative reheating furnace: Considering periodic combustion switching and misalignment contact of walking beams

Improving the billet temperature uniformity is crucial for the quality of rolled products. This paper investigated the heat and mass transfer processes in a regenerative reheating furnace by establishing typical heating unit models. The periodic combustion switching and misaligned water-cooled beams were considered. The effects of furnace temperature oscillation and skid marks on the total heat transfer coefficient distribution and billet temperature uniformity were analyzed. The results indicate that during the heating process of the billet, the periodic variation amplitude of furnace temperature decreases from 86 to 25 °C, and the depth of influence on the billet temperature is about 0.03 m. The total heat transfer coefficient on the billet bottom surface shows a wave distribution affected by beams shielding, but on the top surface, the closer it is to the furnace wall, the smaller the total heat transfer coefficient. The misalignment of water-cooled beams effectively eliminates the original skid mark and reduces the range of new skid mark. However, the cross-sectional temperature difference at the new skid marks remain at about 97 °C. Compared to extending the residence time, increasing the furnace temperature in the soaking zone is the optimal measure to reduce the influence of skid marks.

Improved Test Fixture for Collecting Microcontact Performance and Reliability Data.

Microelectromechanical systems (MEMS) ohmic contact switches are considered to be a promising candidate for wireless communication applications. The longevity of MEMS switches is directly related to the reliability and performance of microcontacts. In this work, an improved microcontact test fixture with high actuation rates (KHz) and highly precise position control (nm) and force (nN) control was developed. Here, we collected microcontact performance data from initial contact tests (ICT) and microcontact reliability data from cold switched tests (CST). To perform these tests with our test fixture, we fabricated MEMS microcontact test structures with relatively high Young's modulus electroplated Nickel (Ni)-based, fixed-fixed beam structure with Au/RuO2 bimetallic microcontacts. These structures were characterized for forces ranging from 200-1000 µN in ICT tests. In a CST test, the tested microcontact survived more than 200 million cycles at a 1 KHz cycle rate, with a stable contact resistance value ranging between 3.8-5.2 Ω. These experiments validate the potentiality of our microcontact test fixture, and will facilitate further investigation on advanced microcontacts to enhance the MEMS switch's reliability.

Significantly enhanced tunneling electroresistance in two-dimensional ferroelectric tunnel junctions realized by reversible Schottky-Ohmic contact switching

Significantly enhanced tunneling electroresistance in two-dimensional ferroelectric tunnel junctions realized by reversible Schottky-Ohmic contact switching

Integrated micro thermoelectric devices with self-power supply and temperature monitoring: Design and application in power grid early warning

The Internet of Things (IoT) and wearable technology have led to the development of wireless sensors at an unprecedented pace. Within the IoT framework, smart grid systems require real-time temperature monitoring of various switch contacts. Especially in the process of power transformation (China: ultra-high voltage → 10 kV → 380 / 220 V), poor switch contact will lead to overheating, resulting in equipment damage and major safety accidents. Micro-thermoelectric devices (micro-TEDs) exhibit a significantly greater thermoelectromotive force than metal-based thermocouples. By establishing two bivariate first-order equations for hot-end and cold-end temperatures, accurate detection of both temperatures and simultaneous self-power supply can be achieved. In this work, we observe that the Seebeck coefficient of hot extruded n-type Bi2Te2.7Se0.3 and p-type Bi0.5Sb1.5Te3 thermoelectric couple exhibits slight fluctuations around 435 μV/K, while its resistivity follows an almost linear trend with temperature from room temperature to 120 °C. By utilizing these two bivariate first-order equations, the temperatures at both the hot and cold ends can be determined. Based on this, we have fabricated a micro-TED (size: 14 × 6 × 2.5 mm3, TE leg: 0.8 × 0.8 × 1.6 mm3) with a temperature measurement accuracy of up to ± 0.1 °C and a power density of 10.12 mW/cm2 under a temperature difference of 30 °C. Furthermore, we used thirteen micro-TEDs and one circuit board to build a self-power supply temperature monitor. When this TE sensor device was deployed on the plum blossom connector surface and conducted online assessments for the 10 kV substation over a span of approximately 200 h, it continuously outputs a temperature signal and the power supply maintained normalcy, exhibiting no aberrations. This temperature monitoring system can be extended to other fields that require all-weather wireless temperature monitoring, which provides a new direction for the development of micro-TEDs.

Experimental and numerical approach to assess the dynamic performance of an inductive ignition system

This paper envisages studying the features of a conventional inductive ignition system along with its MOSFET and IGBT-based transistorized modifications. The influence of mechanical contact breaker dynamics and ignition coil characteristics on the current and voltage waveforms of the primary and secondary circuits of these studied ignition systems are mathematically and experimentally exposed. The investigation is considered necessary prior to attempting subsequent modeling and diagnostics procedures on the current-voltage performance characteristics of conventional and transistorized ignition systems. The work has demanded the development of an experimental setup based on a basic modifiable ignition system mockup and an instrumentation system to measure and analyze the voltage-current parameters of inductive ignition systems. The paper describes the design details of such instrumentation system, presents mechanical and electrical models for contact breaker and ignition circuits, then simulated to obtain base free-run response waveforms and electrical continuity behavior of the contact. A test of frequency response of the ignition coil provided additional input to the model. An experimental test of continuity of the contact, in agreement with its model, shed light on the actual excitation of the primary coil. The work comments on a sample of the registered current and voltage waveforms in primary and secondary coil windings of the ignition system at atmospheric conditions. Comparisons of waveforms and energy for mechanical contact, MOSFET and IGBT switches are made to establish them as a reference for future tests.

Development of a Decommissioning Robot with a Simple Structure Capable of Traversing Steps Using Two Different Drive Systems

In response to the imperative need for robotic involvement in the decommissioning of the Fukushima Daiichi Nuclear Power Plant, a proactive initiative was undertaken. This initiative led to the organization of the “7th Decommissioning Creative Robot Contest,” in which pivotal challenges related to nuclear plant decommissioning were addressed. Recognizing inaccessible areas within a decommissioned plant, the primary objective of this study was to develop a remotely operated robot capable of executing decontamination tasks in such environments. Two distinct locomotion systems were designed: mecanum wheels and crawlers. The mecanum wheels, characterized by their ability to execute approximately 100 mm vertical movements, facilitated the robot to surmount obstacles, particularly by negotiating 100 mm steps by engaging the tracks. Simultaneously, to address decontamination tasks at elevated locations, a threefold expandable ladder truck system was integrated, augmenting the operational range of the robot. Participation in the contest provided a platform for showcasing the developed technologies and validating their practicality. Despite encountering challenges during competition, such as damage to one locomotion system, the other locomotion system can be used to reach the destination. Experience serves as a crucial means of verifying technological advancements. Issues such as malfunctions in the range of motion control due to faulty limit switch contacts and unexpected loads on the tire elevation motors were noted, which hindered the achievement of the anticipated results. Despite these drawbacks, the adopted structural design demonstrates notable advantages, particularly in terms of maneuverability. The combination of mecanum wheels and crawlers along with a ladder truck system demonstrated adaptability to various scenarios. This adaptability holds significant promise for future nuclear power plant decontamination applications. While the competition may not have yielded the desired outcome, the lessons learned and the verified practicality of the developed technologies reinforce their potential utility in addressing the future challenges of nuclear plant decommissioning.

A Flexible Pressure Sensor with Wide Detection Range Based on Capacitive‐Piezoresistive Dual Mode Conversion for Human‐Machine Interaction

AbstractFlexible pressure sensor is widely used in fields such as healthcare, intelligent prosthetics, and patient rehabilitation. However, how to ensure high sensitivity of the sensor while having a wide detection range remains a challenge. In order to address this challenge, a flexible pressure sensor with a wide detection range based on capacitive‐piezoresistive dual mode conversion is proposed. By manufacturing circular through‐holes on the dielectric layer of the sensor, the microstructure of the upper and lower electrode layers can achieve non‐contact and contact switching under different pressures through the through holes. This means that the sensor remains in capacitive mode at low pressure and then in piezoresistive mode at high pressure. By cleverly combining the two modes, the measurement range can reach 2 000 kPa and high sensitivity can be maintained during mode switching. In addition, its production process is simple, the cost is low, and it has a fast response time (120 ms) and good repeatability stability. The experimental results indicate that the sensor can achieve ideal performance in proximity detection, human behavior monitoring, and ultra high‐pressure detection, and has broad application prospects in providing a more powerful human‐computer interaction interface and expanding more comprehensive health monitoring.

The Effect of Laser Surface Remelting on the Surface Properties of Copper

In order to enhance the wear resistance of copper contacts in high-voltage switches and improve the abnormal discharge phenomenon caused by wear gaps, laser remelting technology was used to strengthen the surface of copper contacts. The surface morphology, microhardness, and wear resistance of the remelted samples were tested and characterized using scanning electron microscopy (SEM), microhardness tester, and friction and wear tester. The test results indicate that laser frequency, pulse width, and energy density parameters can directly affect the surface morphology and wear resistance of the sample, but their influencing processes vary. The laser frequency is achieved by the variation in the superposition relationship between the impact points, while the pulse width and energy density are achieved by the variation in the laser intensity at the impact points. When the pulse frequency is 10 Hz, the pulse width is 10 ms, and the energy density is 132.69 J/mm2, the sample exhibits a more balanced surface morphology, microhardness, and wear resistance.

Security, Privacy Challenges and Available Countermeasures in Electronic Health Record Systems: A Review

Electronic Health Record (EHR) systems have revolutionized the healthcare industry by enabling the efficient storage, retrieval, and sharing of patient health information. However, the widespread adoption of EHR systems has also engendered a myriad of privacy and security challenges that must be spoke to guarantee the privacy, integrity, and accessibility of sensitive patient evidence. A range of countermeasures has been implemented to reduce the risks associated with EHR data privacy and security. These include contact switch tools that limit data access to approved operators, as well as advanced encryption methods like Identity-Based Encryption and Attribute-Based Encryption, specifically tailored for securing EHR data in cloud environments. By employing these protective measures, healthcare providers can enhance the safety of sensitive patient information while adapting to the dynamic digital landscape.

Digital circuit for switch contact bounce analysis

This article discusses the issue of studying the parameters of the bounce of electrical contacts of switches in digital systems. Digital circuits of bounce analyzer are described. The results of experimental studies of the behavior of electrical contacts of various buttons and switches are presented. It is shown that various electric switches have random and unique characteristics, which can be used to solve the problems of random numbers generating, identifying of digital devices and user’s authentication. Prototyping of the proposed circuits was carried out on Digilent ZYBO Z7-10 debug boards, digital circuits were designed in VHDL for the Xilinx Zynq-7000 FPGA chip.

Research and experiment the wireless passive surface acoustic wave technology for conductor temperature monitoring of high voltage equipment

This paper presents the research and design of a passive thermal monitoring system using wireless temperature sensors based on the principle of surface acoustic wave (SAW). The monitoring system is employed on components that need to be monitored for heat generation, including switch contacts, busbars, and cable connections at switchgears or ring main units (RMUs). The basic impulse insulation level (BIL), or voltage spike tolerance, of the wireless SAW temperature sensor utilised in this study, means that it is not necessary to power it with sensors that meet the high criteria for equipment installed in closed cabinets or medium voltage cabinets. The research team’s activities in this study included software development, data transmission design and manufacture, and sensor selection. The system functions steadily, with a temperature error of no more than 2oC, according to the test findings under laboratory settings.

Powder metallurgy process enables production of high-strength conductive Cu-based composites reinforced by Cu50Zr43Al7 metallic glass

This study showcases the preparation of Cu50Zr43Al7 metallic glass-reinforced ultrafine grain copper matrix composites using a powder metallurgical process to achieve a superior combination of strength and electrical conductivity. The mechanical ball milling (BM) process is utilized to effectively refine the Cu matrix grains to the nanoscale. Furthermore, high-pressure spark plasma sintering (SPS) is employed to prevent grain growth and improve the interface bonding between two phases. Increasing the Cu50Zr43Al7 addition content improved the mechanical properties under a load transfer strengthening strategy. Notably, the 20 wt% Cu50Zr43Al7/Cu composite demonstrates excellent mechanical properties and high electrical conductivity. This is attributed to the uniformly-dispersed Cu50Zr43Al7 metallic glass particles in the ultrafine grain Cu matrix with well-established interfacial bonding. The synergistic strengthening of the Cu50Zr43Al7/Cu composites represents a novel choice for switch contact materials application, maintaining excellent mechanical properties while satisfying conductive requirements.

A Study of DC Switching Electric ARC Characteristics for Low Voltages

Aims: The purpose of this paper is to investigate the DC electric arc characteristics for low voltages. And explore the relationship among arc time, arc voltage and arc current.
 Study Design: The experimental setup mainly consisted of a switch contact pair, variable resistive load, and a variable power supply. An oscilloscope was used to collect the voltage variations of the switch and the load. The voltage variation data were used to do further analysis.
 Place and Duration of Study: Department of Physics and Electronics, University Of Kelaniya, Sri Lanka between September 2021 and May 2022.
 Methodology: Voltage variations between the contact pair and the load voltage were measured using an oscilloscope for both switching on and off operations. The experiment was performed for four voltage levels; 60 VDC, 80 VDC, 100 VDC, and 120 VDC. For each voltage level, four load conditions were tested. Therein, a total of 16 different conditions were tested. Five tests were done for each condition. The average values were taken for analysis.
 Conclusion: When the switch contacts start to separate, the arc voltage must reach the arc starting voltage to form an arc. Moreover, according to the supply voltage and current, there is always a maximum voltage value that arc can reach, which is less than the supply voltage (arc ending voltage). After the arc was formed in DC systems, the arc voltage variation with time can be modeled using the trigonometry tan function.

Studi keragaan kapal pengawas hiu 02 di Pangkalan Pengawasan Sumber Daya Kelautan dan Perikanan Bitung

The objectives of this study are to determine the amount of fuel consumption within one hour at 600, 1200, and 1700 rpms; describe the operation of the vessel's main engine; and describe the systems in the vessel's main engine. A patrol vessel serves to carry out surveillance and law enforcement against vessels engaged in illegal fishing. In conducting surveillance, the patrol vessel is supported by a main engine, which is a component that propels the vessel. The operation, the main engine requires fuel oil (BBM) to drive the engine. The research findings indicate that : (1) the fuel consumption of the main engine within one hour is 54 liters at 600 rpm, 108 liters at 1200 rpm, and 170 liters at 1700 rpm; (2) the operation of the main engine is carried out by checking the fuel, lubricating oil, cooling water, and opening the fuel valve and seawater valve before starting the engine. Then, turn the engine contact switch from OFF to ON position to enable the ship to move, and to stop the engine, reduce the engine throttle and turn the contact switch from ON to OFF position, and then close the opened valves; (3) The systems in the main engine include the electric starting system, fuel system, wet lubrication system, and closed cooling system.

High-Temperature-Operable Electromechanical Computing Units Enabled by Aligned Carbon Nanotube Arrays.

Nano/micro-electromechanical (NEM/MEM) contact switches have great potential as energy-efficient and high-temperature-operable computing units to surmount those limitations of transistors. However, despite recent advances, the high-temperature operation of the mechanical switch is not fully stable nor repetitive due to the melting and softening of the contact material in the mechanical switch. Herein, MEM switches with carbon nanotube (CNT) arrays capable of operating at high temperatures are presented. In addition to the excellent thermal stability of CNT arrays, the absence of a melting point of CNTs allows the proposed switches to operate successfully at up to 550 °C, surpassing the maximum operating temperatures of state-of-the-art mechanical switches. The switches with CNTs also show a highly reliable contact lifetime of over 1 million cycles, even at a high temperature of 550 °C. Moreover, symmetrical pairs of normally open and normally closed MEM switches, whose interfaces are initially in contact and separated, respectively, are introduced. Consequently, the complementary inverters and logic gates operating at high temperatures can be easily configured such as NOT, NOR, and NAND gates. These switches and logic gates reveal the possibility for developing low-power, high-performance integrated circuits for high-temperature operations.

저압직류계통에서 유도성 부하의 차단아크 특성

This paper studies the characteristics of series arcs during the breaking operation of electric contacts of DC switches or socket outlet and plugs on inductive loads. Through experiments of DC series arc on inductive loads, arc extinction distance and arc transient voltage are analyzed and compared with pure resistive loads. This paper presents the arc-safe operation area according to the opening speed of electrode contacts and the time constants of various inductive loads in low-voltage DC(LVDC) systems.

The Rap1 small GTPase affects cell fate or survival and morphogenetic patterning during Drosophila melanogaster eye development

The Drosophila melanogaster eye has been instrumental for determining both how cells communicate with one another to determine cell fate, as well as cell morphogenesis and patterning. Here, we describe the effects of the small GTPase Rap1 on the development of multiple cell types in the D. melanogaster eye. Although Rap1 has previously been linked to RTK-Ras-MAPK signaling in eye development, we demonstrate that manipulation of Rap1 activity is modified by increase or decrease of Delta/Notch signaling during several events of cell fate specification in eye development. In addition, we demonstrate that manipulating Rap1 function either in primary pigment cells or in interommatidial cells affects cone cell contact switching, primary pigment cell enwrapment of the ommatidial cluster, and sorting of secondary and tertiary pigment cells. These data suggest that Rap1 has roles in both ommatidial cell recruitment/survival and in ommatidial morphogenesis in the pupal stage. They lay groundwork for future experiments on the role of Rap1 in these events.

Self‐powered wireless body area network for multi‐joint movements monitoring based on contact‐separation direct current triboelectric nanogenerators

AbstractBody area network has attracted extensive attention for its applications in athletics, medical, diagnosis, and rehabilitation training in the next generation personalized health care solutions. Here, a contact‐separation direct current triboelectric nanogenerators (CSDC‐TENGs) based self‐powered wireless body area network (SWBAN) is reported that enables multi‐joint movements monitoring for human motion. The CSDC‐TENG is designed as a flexible active sensor with an internal contact switch, and the flexible substrate makes the TENG‐sensor stick onto skin easily. Due to the internal switch, the CSDC‐TENG could generate a DC current, a large instantaneous output voltage exceeds 700 V, and an instantaneous power can reach 1.076 W, which is more than 23 000 times higher than that of the traditional contact‐separation mode TENG in same size and materials without the switch. By coupling with flexible coil, the fixed high‐frequency radio signals can be modulated and emitted clearly ranging from 6 to 16 MHz, which can be wirelessly received and demodulated through a reader. Moreover, the SWBAN is demonstrated in a real time monitoring system for joints motion. This work has realized the wearable TENG for self‐powered wireless real‐time monitoring of body movements driven by low‐frequency human daily activities, which may promote a tremendous development of intelligent healthcare, wireless sensing system and body area network.image