Electricity meters & instrument transformers [antikvár]

PREFACE The advent in Great Britain of the electricity meter as a commercial article dates back to 1880 or thereabouts, and during the intervening years there has been constant improvement in design and manufacture to meet the growing needs of the electricity supply industry. From time to time a new book has appeared dealing with electricity meters, their construction, performance, and testing. Many of these books have been written by engineers connected with the electric supply industry, and few, if any, have been compiled in this country by an engineer closely associated with the manufacture of these instruments. Having spent the greater part of my working life in the designing, manufacturing and testing of electricity meters and accessory apparatus, I have ventured to trespass on this close preserve, in the hope that I may be able to present some of the facts relating to practical meter work as viewed by a manufacturing engineer, and to place on record something new or about which little has been written hitherto should this be possible. Many of the matters dealt with in this volume have been considered in greater detail than is customary in books on meter practice, and it is hoped that this treatment of the subject will be of assistance to the student and the young engineer without being too wearisome to the meter engineer of more mature experience. Mathematical expression has been reduced to a minimum bfrt it was felt that a clear understanding of the working of polyphase and reactive meters could better be achieved by some reference to elementary trigonometry and to vector representation. Two-phase metering is uncommon in Great Britain but reference to this subject has been included for the information of readers overseas, where extensive use is made of two-phase supplies. Considerable practical importance attaches to prepayment meters, of which many are in use. The varieties and types are diverse—much too diverse in my opinion—and it remains to be seen whether simplification and unification of tariffs, which problem is now under consideration by the appropriate authorities, will result in the abandonment of some of the complex devices in use at the present time. The two chapters devoted to prepayment meters are barely sufficient to cover the fringe of a very large subject. The question of tariffs as applied to large power