Buch, Deutsch, 522 Seiten, Format (B × H): 155 mm x 235 mm, Gewicht: 820 g
ISBN: 978-3-662-23790-8
Verlag: Springer
Circuit breakers, relays, terminals, microphones, current collectors and commutators, all operate with electric contacts. Industry is making extensive use of contacts with ever-increasing demands on efficiency. The need of up to date reliable theories as well as of formulas and tables for applications is becoming pressing. This book is an attempt to meet this need. As is the case in many other branches of technology today, problems which arise in the field" of electric contacts involve insight in various other disciplines of physics, including parts which have not yet developed to such an extent that they. are treated in elementary text books. Con sidering the lack of introductions to some topics of this kind it is felt that orienting chapters, for instance, on the tunnel effect, the theory of the arc, the structure of carbon, and the band theory of electric conduction in solids might be valuable for many readers. In order not to burden the main text with such chapters they have been presented as appendices. Several chapters have been devoted to the theory offriction and wear.
Zielgruppe
Research
Autoren/Hrsg.
Weitere Infos & Material
I Stationary Contacts.- II Sliding Contacts.- III Electric Phenomena in Switching Contacts.- IV History.- Appendices.- § I. Hardness, strain hardening, atomic diffusion phenomena as recovery and creep.- A. Survey of the theory of plastic deformation of solid bodies and of diffusion phenomena.- B. Hardness as defined by the ball indentation test.- C. Brittle materials.- D. The work consumed by a plastic deformation.- § II. Electronic conduction in solids.- A. Energy band scheme.- B. Distribution of the electrons on the energy levels of a band, with special reference to the conduction band of a metal.- C. Potential barrier. Thermionic emission of electrons.- E. Semiconduction.- F. Potential barriers and equilibrium conditions in contacts.- § III. Tunnel effect. Thermionic emission and field emission.- A. Theoretical basis for the calculations. Classes I and II of calculation procedure.- C. Tunnel resistivity.- D. Comparison between tunnel current and thermionic current according to formula (III,13).- E. Tunnel effect when both electrodes are of the same semi-conducting material.- F. Remark concerning the field strength.- § IV. Structure, electric and thermal conductivity of carbons.- A. Introduction. Graphite latice.- B. Carbon grades.- C. Graphitization.- D. Electric conductivity of carbons.- E. Heat conductivity of carbons.- § V. Hydrodynamic or thick film lubrication.- § VI. Remarks about threadlike metallic formations.- § VII. Some fundamental formulas concerning the electric discharge.- A. Introduction. Kinetic fundamentals.- B. Drift velocity.- C. Thermal ionization. Saha’s equation.- D. Plasma.- E. Current in vacuum restricted by the space charge of the current carriers.- § VIII. General theory of the arc that appears in relays.- A. Introduction.- B.Reminder of elements of the theory of electric discharges in gases.- C. Thickness of the cathode layer and metal vapor pressure within it.- D. Definition of the examples.- G. Comparison with measurements.- H. Power balance at the cathode.- I. Summary of the results concerning cathode phenomena in arcs between non-refractory electrodes.- J. The power balance at the anode.- K. Cathode of refractory materials as carbon and wolfram.- L. Why is the voltage of a short arc of the order of 10 V?.- M. Movement of the arc spot.- N. Current-voltage characteristics of arcs. Arc life.- § X.- § XI.- Author and literature index.
