Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034794
P. Muller, S. Tenbohlen, R. Maier, M. Anheuser
In this paper, the influences of capacitive and inductive loads on low current arc faults in low voltage switchgear are evaluated. Measurements show, that especially inductive loads have an influence on the frequency spectra of an arc. Several parameters of influence on the arc current could be characterized. It could be shown, that the chance to detect an arc in a grid with several different connected loads depends on the location of the arc and the influence of all loads on the current shape.
{"title":"Influence of Capacitive and Inductive Loads on the Detectability of Arc Faults","authors":"P. Muller, S. Tenbohlen, R. Maier, M. Anheuser","doi":"10.1109/HOLM.2011.6034794","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034794","url":null,"abstract":"In this paper, the influences of capacitive and inductive loads on low current arc faults in low voltage switchgear are evaluated. Measurements show, that especially inductive loads have an influence on the frequency spectra of an arc. Several parameters of influence on the arc current could be characterized. It could be shown, that the chance to detect an arc in a grid with several different connected loads depends on the location of the arc and the influence of all loads on the current shape.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"95 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124093877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034805
Na Lu, L. Xu, Huang Feng, Y.S. Li
The reliability of mobile communication devices is affected by many factors, such as structure design, mechanical and electrical characteristic of devices, electromagnetic disturbance, electrical contact, dynamic environmental, temperature changes, , environmental pollution, etc. Studies show that 14% failure of the electronic products is caused by dust and salt mist. Dust particles ingress electronic device, and contaminate the internal components. This results in electric contact failure and reduced reliability of contact components. It is a very important consideration in electronic product design to protect internal components from operational impairment that due to ingress of dust particles and reduce the impact of dust on the communication device. This paper studies the ability of mobile communication device structure design to resist dust particles ingress and penetration the internal areas. It gives the dust distribution in the mobile phone by experiments and finite element analysis (FEA) using a mobile phone as the representation of the mobile communication device; it provides guidance for structure design and improves reliability of portable electronic products in the future.
{"title":"A Study on Mobile Communication Device Structure Design Resisting Dust Particles Ingress","authors":"Na Lu, L. Xu, Huang Feng, Y.S. Li","doi":"10.1109/HOLM.2011.6034805","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034805","url":null,"abstract":"The reliability of mobile communication devices is affected by many factors, such as structure design, mechanical and electrical characteristic of devices, electromagnetic disturbance, electrical contact, dynamic environmental, temperature changes, , environmental pollution, etc. Studies show that 14% failure of the electronic products is caused by dust and salt mist. Dust particles ingress electronic device, and contaminate the internal components. This results in electric contact failure and reduced reliability of contact components. It is a very important consideration in electronic product design to protect internal components from operational impairment that due to ingress of dust particles and reduce the impact of dust on the communication device. This paper studies the ability of mobile communication device structure design to resist dust particles ingress and penetration the internal areas. It gives the dust distribution in the mobile phone by experiments and finite element analysis (FEA) using a mobile phone as the representation of the mobile communication device; it provides guidance for structure design and improves reliability of portable electronic products in the future.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"59 3","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"113936705","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034775
Kiyoshi Yoshida, K. Sawa, Kenji Suzuki, Masaaki Watanabe, H. Daijima
In this paper, experimental results were described for a general DC electromagnetic contactor switching under a permanent magnet for arc extinguishing. The experiment circuit was a series circuit of source voltage E, resistive load R and DC electromagnetic contactor. The closed contact current Io was adjusted by R. The influence of E and Io on arc duration ta and arc energy Ea of break arc were experimented. The E had been changed within range of 50 -- 500V DC and Io was set from 5 to 30A at each voltage E. Arc voltage and current waveforms were measured with a digital oscilloscope. When E was high, arc duration ta became long. However, in 300V or more, ta shortens when Io is increased. In 200V, influence of Io on ta was not seen and arc duration became almost constant. In 50V, ta became long along with Io, it is clarified that permanent magnets doesn't influence for arc. However, shortening of the arc duration with permanent magnet was seen in 100V or more. We think that effect of Lorentz's force on the arc was different according to E and Io. In addition, when E and Io are high, it was found that arc energy Ea became large. Keywords -- DC electromagnetic contactor, arc discharge, arc duration, magnetic blast, arc energy, permanent magnet
{"title":"Influence of Voltage and Current on Arc Duration and Energy of DC Electromagnetic Contactor","authors":"Kiyoshi Yoshida, K. Sawa, Kenji Suzuki, Masaaki Watanabe, H. Daijima","doi":"10.1109/HOLM.2011.6034775","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034775","url":null,"abstract":"In this paper, experimental results were described for a general DC electromagnetic contactor switching under a permanent magnet for arc extinguishing. The experiment circuit was a series circuit of source voltage E, resistive load R and DC electromagnetic contactor. The closed contact current Io was adjusted by R. The influence of E and Io on arc duration ta and arc energy Ea of break arc were experimented. The E had been changed within range of 50 -- 500V DC and Io was set from 5 to 30A at each voltage E. Arc voltage and current waveforms were measured with a digital oscilloscope. When E was high, arc duration ta became long. However, in 300V or more, ta shortens when Io is increased. In 200V, influence of Io on ta was not seen and arc duration became almost constant. In 50V, ta became long along with Io, it is clarified that permanent magnets doesn't influence for arc. However, shortening of the arc duration with permanent magnet was seen in 100V or more. We think that effect of Lorentz's force on the arc was different according to E and Io. In addition, when E and Io are high, it was found that arc energy Ea became large. Keywords -- DC electromagnetic contactor, arc discharge, arc duration, magnetic blast, arc energy, permanent magnet","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128467603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034818
Yang Lv, Liangjun Xu
Dust particle is an electric cont¬act failure causative factor that must be taken into account. In previous research, [1,2] the effect of dust particles on electric contacts was indicated and simplified model was established for the hazardous size range of hard dust particles entering into the contact interface. The electrical contact behaviors of several typical dusts with different compositions were also studied [3]. As a continuation, the specific characters of dust particle which could cause contact failure are investigated in this paper. The mechanics model of dust particles on contact surface under static and dynamic conditions is built. The mechanics analysis of dust particle on contact interface is performed. Through the sliding experiments of two kinds of dust particles with different bonding strength, failure mechanism and the influence factors on contacts related to dust particles is analyzed and discussed.
{"title":"Stress Analysis of Dust Particle on the Electrical Contact Surface","authors":"Yang Lv, Liangjun Xu","doi":"10.1109/HOLM.2011.6034818","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034818","url":null,"abstract":"Dust particle is an electric cont¬act failure causative factor that must be taken into account. In previous research, [1,2] the effect of dust particles on electric contacts was indicated and simplified model was established for the hazardous size range of hard dust particles entering into the contact interface. The electrical contact behaviors of several typical dusts with different compositions were also studied [3]. As a continuation, the specific characters of dust particle which could cause contact failure are investigated in this paper. The mechanics model of dust particles on contact surface under static and dynamic conditions is built. The mechanics analysis of dust particle on contact interface is performed. Through the sliding experiments of two kinds of dust particles with different bonding strength, failure mechanism and the influence factors on contacts related to dust particles is analyzed and discussed.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130928734","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034807
J. Praquin, C. Gautherot, J. Rivenc, N. Ben Jemaa, E. Carvou, J. B. Mitchell, R. El Abdi
Membrane switching technology is commonly used to operate electrical apparatus such as remote controls, automotive switches, mobile phones, etc. This technology is based on a movable contact, mounted in a supple elastomer frame which allows the contact to be pressed against a stationary contact, mounted on a Printed Circuit Board (PCB). The material of the movable contact is typically a carbon-loaded polymer or a metal whereas the PCB electrode structure is copper, coated with a layer of gold. The current trend is to use this technology for power applications such as operating a coil or a direct actuator control. As reported in the literature, for such currents <1A and inductive loads, microarcs occur between rigid, metallic contacts, during break and make. Their duration and subsequent damage depend highly on the material and the mechanical separation. On the other hand, the high contact resistance of a flexible carbon-loaded polymer and the progressive separation due to its flexibility are expected to modify arc ignition and persistence characteristics. In this paper, we present experimental measurements of the electrical characteristics of such contacts and the consequences of arcing on contact reliability. Long contact rise times of the voltage are found compared to common metallic contacts. These complex voltage characteristics have been analyzed to extract arc voltage and duration. It was found that this supple and resistive contact allows an inductive load to be switched with a minor over-voltage and self-protection against arcing compared to common rigid metallic contacts.
{"title":"A Study of Arc Duration on Supple Carbon Contacts in the Automotive Field","authors":"J. Praquin, C. Gautherot, J. Rivenc, N. Ben Jemaa, E. Carvou, J. B. Mitchell, R. El Abdi","doi":"10.1109/HOLM.2011.6034807","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034807","url":null,"abstract":"Membrane switching technology is commonly used to operate electrical apparatus such as remote controls, automotive switches, mobile phones, etc. This technology is based on a movable contact, mounted in a supple elastomer frame which allows the contact to be pressed against a stationary contact, mounted on a Printed Circuit Board (PCB). The material of the movable contact is typically a carbon-loaded polymer or a metal whereas the PCB electrode structure is copper, coated with a layer of gold. The current trend is to use this technology for power applications such as operating a coil or a direct actuator control. As reported in the literature, for such currents <1A and inductive loads, microarcs occur between rigid, metallic contacts, during break and make. Their duration and subsequent damage depend highly on the material and the mechanical separation. On the other hand, the high contact resistance of a flexible carbon-loaded polymer and the progressive separation due to its flexibility are expected to modify arc ignition and persistence characteristics. In this paper, we present experimental measurements of the electrical characteristics of such contacts and the consequences of arcing on contact reliability. Long contact rise times of the voltage are found compared to common metallic contacts. These complex voltage characteristics have been analyzed to extract arc voltage and duration. It was found that this supple and resistive contact allows an inductive load to be switched with a minor over-voltage and self-protection against arcing compared to common rigid metallic contacts.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125238138","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034813
V. Siddeswara Prasad, P. Misra, J. Nagaraju
Electrical contact resistance (ECR) and coefficient of friction (COF) are the two parameters that characterize the performance of sliding electrical contacts. Due to geometrical minuteness of the electrical and mechanical phenomena occurring at the sliding interface, it has been extremely difficult to develop widely applicable theoretical models and analytical correlations. Consequently, experimental studies gain importance as the contact manufacturers have to depend on the available experimental data. The scope of present work is limited to light duty sliding contacts, which are commonly used in various radio-electronic devices and control and automated systems. Experimental studies conducted on oxygen-free high conductivity (OFHC) Cu contacts are presented in this paper. Effect of normal force, surface roughness, initial run-in, sliding speed, and liquid lubricants on ECR and COF is studied. Experiments are conducted with the help of indigenously developed test setup, consisting of a reciprocating pin-on-flat sliding arrangement. All contacts showed a decrease in ECR with increase in normal force. At small speeds (��U 1.0 mm/s), both ECR and COF are found to be independent of sliding speed. A significant decrease in ECR and COF is observed with progressive sliding during the initial cycles. Roughness of the flat sample is found to have significant effect on ECR and COF, especially during initial sliding cycles. Contacts exhibited an inverse relationship between ECR and COF in the mild wear regime (0.2 < COF ��U 0.4). Liquid lubricants having low viscosity exhibited reasonably low values of ECR and COF for prolonged sliding duration. Presence of wear debris at the sliding zone is found to have significant effect on both ECR and COF. Wear of the sliding surfaces is analyzed using scanning electron microscopy (SEM) and correlated with the observed behavior of ECR and COF.
{"title":"An Experimental Study to Show the Behavior of Electrical Contact Resistance and Coefficient of Friction at Low Current Sliding Electrical Interfaces","authors":"V. Siddeswara Prasad, P. Misra, J. Nagaraju","doi":"10.1109/HOLM.2011.6034813","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034813","url":null,"abstract":"Electrical contact resistance (ECR) and coefficient of friction (COF) are the two parameters that characterize the performance of sliding electrical contacts. Due to geometrical minuteness of the electrical and mechanical phenomena occurring at the sliding interface, it has been extremely difficult to develop widely applicable theoretical models and analytical correlations. Consequently, experimental studies gain importance as the contact manufacturers have to depend on the available experimental data. The scope of present work is limited to light duty sliding contacts, which are commonly used in various radio-electronic devices and control and automated systems. Experimental studies conducted on oxygen-free high conductivity (OFHC) Cu contacts are presented in this paper. Effect of normal force, surface roughness, initial run-in, sliding speed, and liquid lubricants on ECR and COF is studied. Experiments are conducted with the help of indigenously developed test setup, consisting of a reciprocating pin-on-flat sliding arrangement. All contacts showed a decrease in ECR with increase in normal force. At small speeds (��U 1.0 mm/s), both ECR and COF are found to be independent of sliding speed. A significant decrease in ECR and COF is observed with progressive sliding during the initial cycles. Roughness of the flat sample is found to have significant effect on ECR and COF, especially during initial sliding cycles. Contacts exhibited an inverse relationship between ECR and COF in the mild wear regime (0.2 < COF ��U 0.4). Liquid lubricants having low viscosity exhibited reasonably low values of ECR and COF for prolonged sliding duration. Presence of wear debris at the sliding zone is found to have significant effect on both ECR and COF. Wear of the sliding surfaces is analyzed using scanning electron microscopy (SEM) and correlated with the observed behavior of ECR and COF.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133576680","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034800
J. McBride, S. Spearing, L. Jiang, C. Chianrabutra
Material transfer in switching contacts is considered at very low currents, (below 20mA). The transfer process is critical to a wide range of electronic switching technologies and is a limiting factor for MEMs relays. A test system is described and characterized for bench-marking surfaces. This is followed by a study of Multi-walled CNT's (MWCNT's), synthesized on a silicon planar and sputter coated with a gold film. The planar surfaces are mounted on the tip of a piezo-electric actuator and mated with a Au coated hemispherical surface. The switching contacts are tested under conditions typical of MEMS relay applications; 4V, 1mA; with a static contact force of 1mN, results are presented on the bounce process and on the opening characteristic with respect to the melting and boiling voltages for the materials tested.
{"title":"Gold Coated Carbon-Nanotube Surfaces as Low Force Electrical Contacts for MEMS Devices: Part II, Fine Transfer Mechanisms","authors":"J. McBride, S. Spearing, L. Jiang, C. Chianrabutra","doi":"10.1109/HOLM.2011.6034800","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034800","url":null,"abstract":"Material transfer in switching contacts is considered at very low currents, (below 20mA). The transfer process is critical to a wide range of electronic switching technologies and is a limiting factor for MEMs relays. A test system is described and characterized for bench-marking surfaces. This is followed by a study of Multi-walled CNT's (MWCNT's), synthesized on a silicon planar and sputter coated with a gold film. The planar surfaces are mounted on the tip of a piezo-electric actuator and mated with a Au coated hemispherical surface. The switching contacts are tested under conditions typical of MEMS relay applications; 4V, 1mA; with a static contact force of 1mN, results are presented on the bounce process and on the opening characteristic with respect to the melting and boiling voltages for the materials tested.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"82 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"117149269","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034795
Xin Zhou, T. Schoepf
Abstract - Overheated electrical joints due to loose connection are often precursors of electric fires, arc faults, and arc flash in electrical systems. This paper is about the formation mechanism and behavior characteristics of loose connection induced overheated electrical joints. Specific experiments were conducted on busbar joints and systems with currents ranging from 100 A up to 5000 A. The lead time of the overheated contact formation is significantly impacted by the tightening torque of busbar bolts, the amplitude of current, and the proper sizing of electrical joints.
{"title":"Characteristics of Overheated Electrical Joints Due to Loose Connection","authors":"Xin Zhou, T. Schoepf","doi":"10.1109/HOLM.2011.6034795","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034795","url":null,"abstract":"Abstract - Overheated electrical joints due to loose connection are often precursors of electric fires, arc faults, and arc flash in electrical systems. This paper is about the formation mechanism and behavior characteristics of loose connection induced overheated electrical joints. Specific experiments were conducted on busbar joints and systems with currents ranging from 100 A up to 5000 A. The lead time of the overheated contact formation is significantly impacted by the tightening torque of busbar bolts, the amplitude of current, and the proper sizing of electrical joints.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"85 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124941969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034810
K. Sawa, Yasunori Suzuki, N. Morita, T. Ueno, K. Endo
The authors have been investigating degradation process of Au plated slip ring and Ag-Pd brush system. In almost all cases the lifetime of the sliding system ends, when Au plating layer is worn out, the ring surface is oxidized to be black in color and contact resistance becomes very high. However, the lifetime is greatly changed case by case, while it is very short without lubricant. Even with lubricant the lifetime is varied from about 1000 hours to almost 7000 hours in the past experiments. It is an important issue where such variation comes from. In this paper the effect of lubricant on degradation process of contact resistance is focused on. In the past tests the lubricant is supplied only once before the test. In this test the lubricant is regularly supplied almost every 900 operation hours. The followings can be made clear. Just after the supply of the lubricant the contact resistance fall down just for a short time, but it comes back to the similar value before the supply. However the operation more than 8000 hours is realized. In addition the contact voltage drop increase gradually until 2600 hours and after that it stays almost constant around 70mV. It probably means that the Au plating layer is gradually worn out at the stage of increasing voltage drop, while the Ni base plating layer is totally exposed at the stage of constant voltage drop. The reason of long operation seems to be that the lubricant not only decreases wear but also suppresses oxidation of the Ni layer.
{"title":"Effect of Lubricant on Degradation Process of Au-Plated Slip-Ring and Ag-Pd Brush System for Small Electric Power","authors":"K. Sawa, Yasunori Suzuki, N. Morita, T. Ueno, K. Endo","doi":"10.1109/HOLM.2011.6034810","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034810","url":null,"abstract":"The authors have been investigating degradation process of Au plated slip ring and Ag-Pd brush system. In almost all cases the lifetime of the sliding system ends, when Au plating layer is worn out, the ring surface is oxidized to be black in color and contact resistance becomes very high. However, the lifetime is greatly changed case by case, while it is very short without lubricant. Even with lubricant the lifetime is varied from about 1000 hours to almost 7000 hours in the past experiments. It is an important issue where such variation comes from. In this paper the effect of lubricant on degradation process of contact resistance is focused on. In the past tests the lubricant is supplied only once before the test. In this test the lubricant is regularly supplied almost every 900 operation hours. The followings can be made clear. Just after the supply of the lubricant the contact resistance fall down just for a short time, but it comes back to the similar value before the supply. However the operation more than 8000 hours is realized. In addition the contact voltage drop increase gradually until 2600 hours and after that it stays almost constant around 70mV. It probably means that the Au plating layer is gradually worn out at the stage of increasing voltage drop, while the Ni base plating layer is totally exposed at the stage of constant voltage drop. The reason of long operation seems to be that the lubricant not only decreases wear but also suppresses oxidation of the Ni layer.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128255852","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2011-10-06DOI: 10.1109/HOLM.2011.6034796
Per Lindholm
Electrical contacts consists of parts where the surfaces are in contact and where the actual physical contact occur just in a few contact asperity points scattered over the whole apparent contact area. Through these contact spots between the mating bodies the mechanical load and the electric current is transmitted. Often a soft coating is used to enlarge the real contact area. Modeling the mechanical stress on the contacting material includes nonlinear effects of the electric conduction and heat generation as well as the actual mechanical contact of the asperities. A finite element model has been used to study the multiphysics of thermo electromechanical phenomena when two surface asperities are in contact. A three dimensional model describing the asperity size, distribution, normal and shear loads and material property. With geometry of hexagonal shape and symmetrical boundary conditions a larger contact surface of similar roughness can be described.
{"title":"Numerical Study of Asperity Distribution in an Electrical Contact","authors":"Per Lindholm","doi":"10.1109/HOLM.2011.6034796","DOIUrl":"https://doi.org/10.1109/HOLM.2011.6034796","url":null,"abstract":"Electrical contacts consists of parts where the surfaces are in contact and where the actual physical contact occur just in a few contact asperity points scattered over the whole apparent contact area. Through these contact spots between the mating bodies the mechanical load and the electric current is transmitted. Often a soft coating is used to enlarge the real contact area. Modeling the mechanical stress on the contacting material includes nonlinear effects of the electric conduction and heat generation as well as the actual mechanical contact of the asperities. A finite element model has been used to study the multiphysics of thermo electromechanical phenomena when two surface asperities are in contact. A three dimensional model describing the asperity size, distribution, normal and shear loads and material property. With geometry of hexagonal shape and symmetrical boundary conditions a larger contact surface of similar roughness can be described.","PeriodicalId":197233,"journal":{"name":"2011 IEEE 57th Holm Conference on Electrical Contacts (Holm)","volume":"101 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2011-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116544174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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