Tài liệu Fundamentals of Electrical Contacts doc

Part I Fundamentals of Electrical Contacts Milenko Braunovic ´ , Valery V. Konchits, and Nikolai K. Myshkin 1 q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC q 2006 by Taylor & Francis Group, LLC [...]... are induced in the state of the mated surfaces In this case the voltage across open contacts is less than the softening voltage The most important and widely used types of sliding contacts include contacts of electrical machines, current pick-offs of transport and lifting machines, and of radio-electronic devices, and control and automatic systems As a rule, sliding contacts for electrical and transportation... Electric Contacts (1958) The 50 years following its publication have given a firm confirmation of the accuracy of his predictions and conclusions Since that time, however, there has been a huge increase in the application of electrical contacts For example, the era of the information highway and the development of the integrated circuit have created new challenges in the use of electrical contacts The use of. .. Processes 370 9.1.2 Role of Boundary Films 371 9.1.3 Main Means of Improving Reliability of Sliding Contacts 371 9.1.4 Tribophysical Aspects in the Development of Sliding Contacts 373 9.2 Dry Metal Contacts 376 9.2.1 Low-Current Contacts 376 9.2.1.1 Effects of Low Current and Electrical Field on Friction 377 9.2.1.2 Effect of Interfacial Shear ... LV, MV electrical equipment fond on the company web site (http://www.squared.com) Prof L.K.J Vandamme of the Department of Electrical Engineering, Eindhoven University of Technology, The Netherlands for providing and allowing the use of reference materials concerning the noise in electrical connections Mr Larry Smith of USi, Armonk, NY, USA, for permitting the use of the images and descriptions of the... depends upon the passage of electricity through an electrical contact at least once The failure of an electrical contact has resulted in severe consequences, e.g., an energy collapse of a megapolis, a failure of the telephone system, and even the crash of an airplane Ragnar Holm, the prominent researcher, renowned engineer, and inventor, developed the validity of electrical contacts as its own technical... Stability of the Contact Resistance Electrical Noise 400 9.2.3.1 Contact Noise in Closed Connections 400 9.2.3.2 Electrical Noise in Sliding Contacts 402 Lubricated Metal Contacts 414 9.3.1 Introduction Lubrication Factors 414 9.3.2 Electrical Properties of Lubricating Boundary Layers 415 9.3.3 Conductivity of Lubricated Contacts 419 9.3.3.1 Effect of Lubricant... Aspects of Lubrication 438 9.3.4.4 Effect of Velocity in Light-Current Contacts 441 9.3.4.5 Effects of Lubricant Contact Properties 442 9.3.4.6 Current Passage and Friction in High-Current Lubricated Contacts 444 9.3.5 Lubricants for Electrical Contacts 449 9.3.5.1 Lubricants for Sliding Electric Switch Contacts 450 9.3.5.2 Lubricants for Sliding Contacts of Sensors... “Lubricating” Effect of Electrical Current 471 9.4.2.1 Effect of Current on Friction Characteristics 471 9.4.2.2 Mechanism of the “Lubricating” Action of the Electric Current 473 9.4.2.3 Effect of Brush Material on Friction Behavior with Electric Current 477 9.4.3 Electrical Wear 479 9.4.3.1 Wear of Currentless Contacts 479 9.4.3.2 Effect of Current on Wear... Slider Current Rheostats, pickoffs of potentioelectrical meters and welding code machines senders Commutating Trolley Separable Current pickoffs of cranes and transport Relay Breaking Plug connectors and circuit breakers Operate under conditions of friction and wear FIGURE 1.1 Classification of electrical contacts deformation The lower the specific resistance and hardness of a material, the higher its... materials used; † Sliding contacts with a moderate electrical contact load are contacts where mechanical, thermal or electrical effects, excluding sparking and arcing, change the state of the mated surfaces The voltage across opened contacts is between the softening voltage and the minimal electric arc voltage for the material used; † Sliding contacts with a low electrical contact load are contacts where no . era of the information highway and the development of the integrated circuit have created new challenges in the use of electrical contacts. The use of electrical contacts. and management of a broad range of research projects for Hydro-Que ´ bec and the Canadian Electrical Association in the areas of electrical power contacts,