Contact Switch Research Articles

Outrush Current Control by Hot Swap Controller for Battery Protection in Electrical Vehicle

This paper focuses on problem-solving for large outrush current from DC power supply to capacitive load in an electric vehicle. This outrush current occurs during a pre-charge state of traction battery to cause high spike peak and consequently damage the main switching contact and the battery cell. In this paper the current control to gradually increase the outrush current by hot swap controller was proposed. The responses of the proposed control and the classical control were compared and investigated. With the proposed control technique, the impact of harmful outrush current can be reduced. As a result, the hot swap controller gave satisfactory responses and provided good stability.

Finite element based contact analysis of radio frequency MEMs switch membrane surfaces

Finite element simulations were performed to determine the contact behavior of radio frequency (RF) micro-electro-mechanical (MEM) switch contact surfaces under monotonic and cyclic loading conditions. Atomic force microscopy (AFM) was used to capture the topography of RF-MEM switch membranes and later they were analyzed for multi-scale regular as well as fractal structures. Frictionless, non-adhesive contact 3D finite element analysis was carried out at different length scales to investigate the contact behavior of the regular-fractal surface using an elasto-plastic material model. Dominant micro-scale regular patterns were found to significantly change the contact behavior. Contact areas mainly cluster around the regular pattern. The contribution from the fractal structure is not significant. Under cyclic loading conditions, plastic deformation in the 1st loading/unloading cycle smooth the surface. The subsequent repetitive loading/unloading cycles undergo elastic contact without changing the morphology of the contacting surfaces. The work is expected to shed light on the quality of the switch surface contact as well as the optimum design of RF MEM switch surfaces.

High-Power High-Isolation RF-MEMS Switches With Enhanced Hot-Switching Reliability Using a Shunt Protection Technique

This paper presents a shunt protection technique to improve the hot-switching reliability of metal-contact radio-frequency microelectromechanical systems (RF-MEMS) switches. The proposed technique places shunt protection contacts in front of the main contact of an RF-MEMS metal contact switch to block RF signal while the main contact is switching ON or OFF. The shunt protection contact creates a local cold-switching condition for the main contact to increase the lifetime of the switch under hot-switching condition. The shunt protection technique can also increase the overall isolation of the switch. To demonstrate the technique, RF-MEMS switches with and without shunt protection were fabricated using all metal process. Compared with the unprotected switch, the protected switch has longer lifetime under hot-switching condition. The protected switch has >100-million cycles and up to 500-million cycles lifetime under the 1-W hot-switching condition, measured in open-air laboratory environment. Besides, the isolation of the shunt-protected switch is 70 dB at 1.0 GHz and 36 dB at 40 GHz, and the insertion loss is 0.30 dB at 1.0 GHz and 0.43 dB at 40 GHz.

Остаточные напряжения как возможная причина повреждения оборудования и риска для персонала при отключении воздушных линий электропередачи. Часть 1

To prevent substation equipment damage and to ensure safety of substation personnel under high voltage and extremely high voltage (EHV) overhead transmission line (TL) outage on the example of 500 kV TL outage voltages between switchable phase switch contacts are calculated. It is shown that under operating in the idle mode EHV TL outage, after arc clearing between switch contact connected to the phase at TL beginning and earth aperiodic voltage with the highest value exceeding the peak value of nominal phase voltage is created.The switch contact connected to the mains voltage, relative to the ground remains periodic nominal phase voltage. The resulting voltage between open contacts of the switch becomes aperiodic shifted periodic voltage with highest value exceeding the double peak value of nominal phase voltage that can cause breakdown of the switch. If there is a break switch phase, it will light the arc and switch under arc will go idle mode operating current, the voltage will recover to idle mode value, the current will stop, the arc goes out, aperiodic voltage will appear, etc. Such a process in a closed cycle can last a long time. Thus, output voltages high values can cause breakdown along the switches surface, damage to switches and health risk factor for the staff performing the bypass substation.

Design and realization of high voltage disconnector condition monitoring system

The operation status of the high voltage disconnector directly affects the safe and stable operation of the power system. This article uses the wireless frequency hopping communication technology of the communication module to achieve the temperature acquisition of the switch contacts and high voltage bus, to introduce the current value of the loop in ECS, and judge the operation status of the disconnector by considering the ambient temperature, calculating the temperature rise; And through the acquisition of the current of drive motor in the process of switch closing and opening, and fault diagnosis of the disconnector by analyzing the change rule of the drive motor current, the condition monitoring of the high voltage disconnector is realized.

The Research and Implementation of Intelligent Judgment about Bus Switching Based on the Automation System

The design of the GIS (Gas Insulated Switchgear) equipment fully enclosed, when it reduces the problem of interference caused by the external environment and reduces the substation area, it also makes the operator cannot directly observe the status of the device. When the mechanism box cover of knife switch rust, or internal components of knife switch rust, or the actual switching contacts are not in place, but the knife switch position indicator indicating closing, it will easily cause charged prone to pull the knife switch accident happen, especially in the switching operation of the bus, the problem is more prominent. Aiming at the risk of status of the knife position can go wrong, and combined with the current status of the substation, this paper proposes a technology program of intelligent assist judgment about bus switching based on the automation system, which use bus power balance principle and the principle of the three-phase current balance to achieve GIS knife in the switching operation process to determine the location of the intelligent Assistant. This paper uses historical data of scheduling sequence database and historical data of substation automation system to verify the reliability of the algorithm. The intelligent auxiliary judgment module for bus switching based on this paper has been deployed in many substations and verified through switching operation many times, it has good promotional value.

Transformer Oil Dielectric Strength in the Contact Gap of the Explosive Arc-Extinguishing Device

The article describes the experimental results on the breakdown of the high-speed flow of transformer oil. In real conditions, the flow moves in the contact gap of a high-voltage explosive switch with speeds from 67 to 152 m / s. The geometry of the contact gap is sharply inhomogeneous and forms turbulence in the flow zone. In the arc chute medium the air inclusions pass from the dissolved state to the gaseous and the emerging bubbles enter to the electric field. Breakdown occurs, mainly through gas inclusions. In the moment, the gradient of the breakdown voltage is reduced by 91.6% compared to the static state of the oil. The experiments were carried out on the model of a high-voltage explosive switch, connected to the power circuit of the surge generator. The probing of the gap was made by a standard pulse of 1.5 / 50 μs. As a result, the dependences of the gradient of the breakdown voltage on the flow rate of the transformer oil for the usual geometry of the high-voltage explosive switch contact system are constructed.

A Joint Vibration and Arcing Measurement System for Online Condition Monitoring of Onload Tap Changer of the Power Transformer

Vibration measurement has been adopted in some utilities in Australia, Canada, and several European countries for online condition monitoring of the power transformer's onload tap changer (OLTC). By comparing measured vibration signals at different stages, it might be possible to assess changes of OLTC's condition. However, there are still considerable difficulties in correlating vibration signals to the events of OLTC operation, which may impair the capability of vibration measurement for OLTC condition monitoring. Therefore, arcing measurement is proposed in this paper to complement the vibration measurement. Arcing is provoked when the OLTC switching contact closes at a fixed tap position and can lead to electromagnetic signals flowing through transformer windings, finally reaching earth. The arcing measurement is achieved by using a high-frequency current transducer (HFCT) clamping on the transformer's grounding cable. The joint vibration and arcing measurement can provide a better means for interpreting events involved in OLTC operation and facilitating improved OLTC condition monitoring. Since HFCT measured arcing signals can be coupled with noise, a probabilistic wavelet transform is thus employed in this paper to extract arcing signals from noise. Field measurements on two different types of OLTCs are performed using the joint vibration and arcing measurement system to validate the proposed methodology.

A model-based measurement method for intelligent circuit breaker with data communication

In this paper, an object-oriented information model of an intelligent vacuum circuit breaker based on its physical structure and function (service) was established to integrate the measuring information flow of field parameters, the monitoring information flow of status data, and the operating and controlling information flow. The status parameters of the intelligent vacuum breaker were detected by analysing the principles and methods based on IEC61850 and IEC62271 standards. The IEC 61850 standard repository can be extended according to the characteristics of the intelligent vacuum breaker status parameters, and the IED server model was constructed to be suitable for the vacuum breaker. A key feature of the new method is the use of a multimode fibre that is incorporated into the IED server model to transmit the status parameters from the target to the sensor. The main characteristic of the measurement method is that it exhibits real-time transmission of data collection. The model includes temperature testing of the switch contact, vacuum arc testing, detection of vacuum switch motion and primary circuit parameters testing. Furthermore, we show how the IEC61850 standard can be used to give a better insight on data communication of the data collector and intelligent circuit breaker. Experimental results showed that the feasibility of intelligent vacuum breaker status monitoring through the switching-on test. It purposes to achieve information integration and a frame communication platform for the intelligent vacuum breaker.

Contact Welding Mechanism With Bounce Arc on Ag and Cu Contacts in Low-Voltage Switches

This paper describes a basic mechanism of contact welding formed by bounce arc upon contact making, based on experiments and analytical simulation of thermal conduction in the contact. We measured the weld force after every contact making in a low-voltage condition (200 V ac). The arc current was set to 60–500 A using a reactor load, the arc duration was within 0.12–2.42 ms, and the contact materials were pure silver (99.99%) and copper (99.9%). In this condition, we clarified that the weld force increases depending on arc energy supplied to the contact surface. We also measured the melted area on the contact surface and clarified the area dependence on the arc energy. Considering the tensile strength of the contact material, we found that the real welded area corresponds to about 25%–40% of the melted area. We concluded that the evaporation of contact material is a significant factor in reduction of the welded area.

Study of dynamic contacts for graphene nano-electromechanical switches

We study graphene–metal static contacts by fabricating the transmission line model (TLM) pattern on a graphene nanoribbon (GNR) and dynamic contacts by GNR nano-electromechanical (GNEM) switches with and without periodic concave patterns on the suspended top electrode. A negative contact resistance extracted from the results of TLM analysis is attributable to the inhomogeneity of GNRs owing to the doping from the metal and the substrate. All the dynamic contacts in GNEM switches show clear pull-in operations, which are not reversible. GNEM switches with periodic arrays of concave contacts show global pull-in onto the bottom surface of the concave and then exhibit local pull-in onto the slanted sidewall surfaces of the concave, which is confirmed by finite element method simulation. In addition, plastic deformation at the contact is observed as a result of the local pull-in failure mode, which completely hinders the GNRs from pulling out from the contact surface.

The Architecture of Respiratory Supercomplexes

Mitochondrial electron transport chain complexes are organized into supercomplexes responsible for carrying out cellular respiration and energy production. The majority of complex I in heart mitochondria is found bound with a complex III dimer and complex IV (CICIII2CIV, the respirasome) or with a complex III dimer alone (CICIII2). Here I will present three architectures of mammalian (ovine) supercomplexes determined by cryo-electron microscopy. We identify two distinct arrangements of the respirasome—a major ‘tight’ form and a minor ‘loose’ form (resolved at the resolution of 5.8 Å and 6.7 Å, respectively), which may represent different stages in supercomplex assembly or disassembly. We have also determined an architecture of supercomplex CICIII2 at 7.8 Å resolution. All observed density can be attributed to the known 80 subunits of the individual complexes, including 132 transmembrane helices. The individual complexes form tight interactions that vary between the architectures, with complex IV subunit COX7a switching contact from complex III to complex I. The arrangement of active sites within the supercomplex may help control reactive oxygen species production. These are the first complete architectures of the dominant, physiologically relevant state of complex I in the electron transport chain.

The Penultimate Tyrosine Residues are Critical for the Genotoxic Effect of Human Hemoglobin.

Hemoglobin (Hb) is a potent oxidant outside the erythrocyte. The tyrosines α140 and β145 play an important role in the structure and function of Hb by forming switch and hinge contacts. These carboxy-terminal residues of the alpha and beta chains, respectively, were replaced to phenylalanine and several different methods were used to characterize the obtained mutants including a comet and plasmid DNA cleavage assay. It was observed that the genotoxic effect was 40% higher for αY140F compared with the wildtype, the βY145F and the double (αY140/β145F) mutants as determined by the comet assay. Cleavage of purified plasmid DNA after Hb application also revealed that the αY140F mutant showed 2-fold higher activity, while the βY145F and αY140/β145F mutants reduced the activity compared to wildtype Hb. This study clearly indicates that the penultimate tyrosines are involved in the genotoxicity of Hb.

Global planning of whole-body manipulation by humanoid robot based on transition graph of object motion and contact switching

Humanoid robot has the potential to achieve various manipulation strategies such as lifting, pushing, pivoting and rolling. Deciding which strategies to apply for the object manipulation is difficult because the appropriate manipulation motion varies greatly depending on the object property. We propose the planning method of whole-body manipulation for various manipulati on strategies. In order to plan the manipulation in the global scope, we generate the graph representing all the possible object poses and operation contacts. By searching the feasible path in the graph, we plan the sequence of object states satisfying the kinematics and dynamics conditions. Finally, the robot postures for the whole-body manipulation are generated from the object states. The proposed method is efficient because the tractable object configuration is first planned in the global scope and then the complicated robot configuration is calculated. We show the effectiveness of the proposed method by planning the humanoid robot motion for various manipulation strategies automatically from the object and robot models.

Mechanisms of Contact, Adhesion, and Failure of Metallic Nanoasperities in the Presence of Adsorbates: Toward Conductive Contact Design.

The properties of contacting interfaces are strongly affected not only by the bulk and surface properties of contacting materials but also by the ubiquitous presence of adsorbed contaminants. Here, we focus on the properties of single asperity contacts in the presence of adsorbates within a molecular dynamics description of metallic asperity normal contact and a parametric description of adsorbate properties. A platinum-platinum asperity contact is modeled with adsorbed oligomers with variable properties. This system is particularly tailored to the context of nanoelectromechanical system (NEMS) contact switches, but the results are generally relevant to metal-metal asperity contacts in nonpristine conditions. Even though mechanical forces can displace adsorbate out of the contact region, increasing the adsorbate layer thickness and/or adsorbate/metal adhesion makes it more difficult for metal asperity/metal surface contact to occur, thereby lowering the electrical contact conductance. Contact separation is a competition between plastic necking in the asperity or decohesion at the asperity/substrate interface. The mechanism which operates at a lower tensile stress dominates. Necking dominates when the adsorbate/metal adhesion is strong and/or the adsorbate layer thickness is small. In broad terms, necking implies larger asperity deformation and mechanical work, as compared with decohesion. Optimal NEMS switch performance requires substantial contact conductance and minimal asperity deformation; these results indicate that these goals can be achieved by balancing the quantity of adsorbates and their adhesion to the metal surface.

Improved Workability of the Nanocomposited AgSnO2 Contact Material and Its Microstructure Control During the Arcing Process

There are two major weaknesses for the AgSnO2 contacts used in the low voltage switch devices. One is poor workability, which causes the AgSnO2 materials to hardly deform into the required shape. Another is the increased contact resistance after arcing, which, in turn, causes an unfavorable temperature rise in the switches. In this article, the nanocomposited AgSnO2 materials were developed to overcome the weaknesses. The nanosized SnO2 powders with or without CuO additive were prepared by the chemical precipitation method. The SnO2 powders and Ag powders were high energy milled together to obtain AgSnO2 composite powders, which were then sintered, hot pressed and extruded. It was found that the SnO2 particles mainly distribute in the interior of Ag grains with Ag film on the grain boundary. The hardness of AgSnO2 composites and the wetting angle of Ag melt on SnO2 particles decreased with the addition of a small amount of CuO. By the combining effect of Ag film on grain boundary and the addition of CuO, the elongation and workability of the AgSnO2 materials improved. The experiments of rapid solidification revealed that more SnO2 particles with CuO addition were engulfed in the Ag matrix than those without CuO, which inhibited the redistribution of SnO2 particles on the contact surface during the arcing process. The industrial type test in the 45A contactor suggested that the nanocomposited AgSnO2 materials are suitable to be used as contacts in low voltage switches.

The architecture of respiratory supercomplexes.

Mitochondrial electron transport chain complexes are organized into supercomplexes responsible for carrying out cellular respiration. Here we present three architectures of mammalian (ovine) supercomplexes determined by cryo-electron microscopy. We identify two distinct arrangements of supercomplex CICIII2CIV (the respirasome)-a major 'tight' form and a minor 'loose' form (resolved at the resolution of 5.8 Å and 6.7 Å, respectively), which may represent different stages in supercomplex assembly or disassembly. We have also determined an architecture of supercomplex CICIII2 at 7.8 Å resolution. All observed density can be attributed to the known 80 subunits of the individual complexes, including 132 transmembrane helices. The individual complexes form tight interactions that vary between the architectures, with complex IV subunit COX7a switching contact from complex III to complex I. The arrangement of active sites within the supercomplex may help control reactive oxygen species production. To our knowledge, these are the first complete architectures of the dominant, physiologically relevant state of the electron transport chain.

(Invited) Highly Functional Graphene Nano-Electromechanical (GNEM) Devices for Advanced Switch and Sensor Applications

Graphene, as a monolayer of graphite, has an ultra-high Young’s modulus of ~1 TPa, which makes it a promising candidate for Nano-Electromechanical (NEM) devices. The graphene NEM switches is expected to show minimized electrical leakage, sharp switching response, low actuation voltage, and high on/off ratio. A simple bottom-up procedure using a polymer sacrificial spacer is utilized to fabricate graphene electromechanical contact switch devices. Low pull-in voltage of below 5 V is achieved with good consistency [1], which is compatible with the conventional complementary metal-oxide-semiconductor circuit requirements. In addition, the formation of carbon-gold bonds at the contact position is proposed as another important mechanism for the irreversible switch other than the well-known irreversible static friction. In order to overcome the stiction issue and realize repetitive switching operations, we exploited a natural chromium oxide layer formed on the chromium electrode. We fabricated a doubly-clamped beam and cantilever graphene nanoelectromechanical switches with a local top actuation electrode. The low pull-in voltage below 5 V was realized in both of the switches. The naturally formed chromium oxide at the graphene-electrode contact interface prevents the formation of chemical bonds between graphene and metal, resulting in reversible switching operation successfully. Thanks to highly-stable SP2 bonds in a 2D honeycomb lattice, graphene exhibits an extremely suppressed electrical noise, making it possible to realize extremly-sensitive sensor. For the physisorbed CO2 molecules - graphene vdW complexes, we found it is possible to tune the vdW interaction with external electric fields. The field-dependent charge transfer in the CO2−graphene complex was unveiled along with small variations in the equilibrium CO2−graphene distance and the O−C−O bonding angle. By reversing the substrate bias polarity, the charge transfer direction also switched, signifying the role of physisorbed CO2molecules can be altered electrically between donor and acceptor. The range of such electrical tunability was found inherent in individual molecular species [2]. In recent years, direct milling of graphene by Helium ion beam (HIB) has been actively explored. The main advantages of HIB milling over typical gallium focused ion beam (FIB) milling are: high resolution and less damage to the graphene. This HIB milling can be actively explored to carve the suspended graphene into a very narrow beam, which will help to realize narrower suspended graphene beams, which can’t be realized with the standard electron beam lithography technique. Towards this direction, gas field ionization source (GFIS) system with Helium and Nitrogen beams is introduced. In order to use HIB milling, a suspended monolayer graphene beam device was first fabricated without a top gate. These devices were used for the further HIB milling. We successfully patterned a 60-nm-long and 15-nm wide suspended graphene beam. As the next step to utilize our unique graphene nano-electro-mechanical systems (NEMS) to realize a well challenging application, the NEMS sensor devices were explored to realize individual CO2 molecule detection. Detection of a single molecule’s adsorption and desorption, which determines the ultimate resolution of gas sensing, has rarely been achieved with conventional solid-state sensor devices. A doubly clamped bilayer graphene beam was first fabricated and then by applying a voltage to the lower gold electrode the graphene beam was electrostatically pulled down. It was found that despite the negligible charge transfer from a single very poor doping CO2 physisorbed molecule, it strongly affects the electronic transport in suspended graphene beam by inducing charged impurity, which can shut down part of conduction of the graphene channel with Coulomb impurity scattering. We detected each individual physisorption of CO2molecule as a step-wise resistance change with a quantized interval for the graphene channel [3].

An Ultra Wideband, Novel and Reliable RF MEMS Switch

This paper presents the design and characterization of wide band ohmic microswitch with an actuation voltage as low as 20~25 V, and a restoring force of 14.1 μN. The design of the proposed switch is primarily composed of an electrostatic actuator, bridge membrane, cantilever (beam) and coplanar waveguide, suspended over the substrate. The analysis shows an insertion loss of −0.002 dB at 1GHz and remains as low as −0.35 dB, even at 100 GHz. The isolation loss of the switch is sustained at −21.09 dB at 100GHz, with a peak value of −99.58 dB at 1 GHz and up-state capacitance of 4 fF. To our knowledge, this is the first demonstration of a series contact switch, which works over a wide bandwidth (DC-100 GHz) and with such a high and sustained isolation, even at high frequencies and with an excellent figure of merit (f_c=1/2.pi.Ron.Cu= 39.7 THz).

A 3-D Steady-State Analysis of Thermal Behavior in EHV GIS Busbar

Busbar has been used as electric conductor within extra high voltage (EHV) gas insulated switchgear (GIS), which makes EHV GIS higher security, smaller size and lower cost. However, the main fault of GIS is overheating of busbar connection parts, circuit breaker and isolating switch contact parts, which has been already restricting development of GIS to a large extent. In this study, a coupled magneto-flow-thermal analysis is used to investigate the thermal properties of GIS busbar in steady-state. A three-dimensional (3-D) finite element model (FEM) is built to calculate multiphysics fields including electromagnetic field, flow field and thermal field in steady-state. The influences of current on the magnetic flux density, flow velocity and heat distribution has been investigated. Temperature differences of inner wall and outer wall are investigated for busbar tank and conducting rod. Considering the end effect in the busbar, temperature rise difference is compared between end sections and the middle section. In order to obtain better heat dissipation effect, diameters of conductor and tank are optimized based on temperature rise simulation results. Temperature rise tests have been done to validate the 3-D simulation model, which is observed a good correlation with the simulation results. This study provides technical support for optimized structure of the EHV GIS busbar.