Electricity Control

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Text extracted from opening pages of book: ELECTRICITY CONTROL: H treatise ON ELECTRIC SWITCHGrEAR AND SYSTEMS OP ELECTRIC TRANSMISSION. BY LEONARD ANDREWS, ASSOCIATE MEMBER OP THE INSTITUTION OF OIVIL ENGINEERS, MEMBER OF THE INSTITUTION OF ELECTRICAL ENGINEEES, EX-MEMBER OF COUNCIL OF THE INCORPORATED MUNICIPAL ELECTRICAL ASSOCIATION, ETC., ETC. With 2 flMates anb 204 figures in tbe LONDON: CHARLES GRIFFIN AND COMPANY, LIMITED, . EXETER STREET, STRAND. 1904. All Rights Reserved, ] PRINTED BY NEILL AND COMPANY, LIMITED EDINBURGH. PREFACE. ELECTEICAL engineers have such an enormous library from, which to select their technical literature that to increase its dimensions must be considered an offence, unless it can be shown that there is room for a new book on any particular subject. My excuse for so trespassing must be that, although many books exist on boilers, engines, electric generators, mains, transformers, lamps, etc., no one has dealt exclusively with that part of the system that has been rightly termed the' nerve centre.' A reason for this apparent neglect of a very important section is to be found in the fact that such rapid advances in switchgear design are daily being made that it is almost impossible for a book, which necessarily is some months in passing through the press, to be absolutely up-to-date. It should be explained at the outset that the present work does not pretend to be purely a record of the best modern practice in switchgear design. Quite a large proportion of it is devoted to descriptions of various kinds of apparatus that have been abandoned, with, in many cases, a brief explanation of the reasons of failure. Some engineers claim that their time is toovaluable to waste in endeavouring to understand failures, and they are quite content to be guided in the preparation of their schemes by the dictates of fashion. But to the engineer who, when he meets a difficulty, is not satisfied until he has got to the bottom of it to the designer who will often make efficient use of a device that has failed by applying it to another purpose, and to the student who conscientiously wishes to prepare to deal with the difficulties he may meet with in his after career the brief records given of difficulties that have been encountered in the evolution of modern switchgear will, I trust, prove of some assistance. There are certain classes of switchgear that I have not attempted to deal with, such as small installation switches, motor controllers, and automatic pressure regulating devices, all of which might have come within the scope of the work; but the subject as a whole is such an inexhaustible one that I have thought it best to confine my attention to VI PREFACE. the control of that portion of the system between the generators and the distributing centre. I wish to take this opportunity of thanking the many friends who have assisted nie in this work, particularly the engineers and manufacturers who have lent me drawings and blocks and furnished me with full information respecting their designs. My thanks are especially due to my friends, Mr A. H. Foyster and Mr C. S. Thomson, for the great assistance they have given me in correcting the proofs, and to my late assistant, Mr C. Hanna, by whom over 150 of the line drawings and diagrams with which the book is illustrated were drawn. The majority of these were specially designed with a view to showing assimply and clearly as possible in one illustration those features of the apparatus to which it was desired to draw attention. I must also acknowledge the help of another old assistant, Mr C. Coleman, who, in the small hours of many a night during the past ten years, has assisted me in carrying out the various experiments referred to. LEONARD ANDREWS. CROMWELL CHAMBERS, MANCHESTER, September 1904. CONTENTS. CHAPTER I. GENERAL PRINCIPLES OF SWITCHGEAR DESIGN. PAGE Introductory remarks The great importance of simplicity Advantage of single-pole switcligear for earthed s