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CENTRAL ELECTRICAL STATIONS: Their Design, Organisation, and Management. By CHAS. H. WORDINGHAM, A.K.C., M.Inst.C.E., M.I.Mech. E. SECOND EDITION. Revised. Large 8vo. With Plates, Diagrams, and Figures. Price 24s. net. "The volume will be studied with eagerness and appreciation."-Scottish Electrician. ELECTRICITY CONTROL: A Treatise on Electricity Switchgear and Systems of Transmission. By LEONARD ANDREWS, M.I.E.E. Large 8vo. Fully Illustrated. Price 12s. 6d. net. ELECTRICAL RULES AND TABLES: For the use of Electricians and Engineers. By JOHN MUNRO, C.E., and PROFESSOR JAMIESON, M. Inst.C.E., F.R.S.E. SEVENTEENTH EDITION. Pocket size. With numerous Diagrams. In Leather. Price 8s. 6d. "Wonderfully perfect. Worthy of the highest commendation."-Electrician. ELECTRICAL PRACTICE IN COLLIERIES. By D. BURNS, M.E., M.Inst.M.E. A book for Colliery Managers, Engineers, and Students. SECOND EDITION. Crown 8vo. Handsome cloth. With numerous Illustrations. Price 7s. 6d. net. "Excellent, both in style and substance."-Glasgow Herald.

ELECTRO-METALLURGY: Embracing the application of Electrolysis to the Plating, Depositing, Smelting, and Refining of various Metals, and to the Reproduction of Printing Surfaces and Art Work. By WALTER G. MCMILLAN, F.I.C., F.C.S. SECOND EDITION. Revised and Enlarged. Large Crown 8vo. Price 10s. 6d. "An excellent treatise. .. one of the BEST AND MOST COMPLETE manuals."-Electrical Review. ELECTRIC SMELTING AND REFINING: A Practical Manual of the Extraction and Treatment of Metals by the Electrical Methods. By DR W. BORCHERS. Translated by W. G. McMILLAN, F.I.C., F.C.S. Large 8vo. Handsome cloth. SECOND EDITION. Thoroughly Revised and Enlarged. 21s. net.

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WIRELESS TELEGRAPHY: By DR GUSTAV EICHHORN. 8vo. Handsome Cloth. With 79 Illustrations. LUBRICATION AND LUBRICANTS: A Treatise on the Theory and Practice of Lubrication. By LEONARD_ARCHBUTT, F.I.C., F.C.S., and R. MOUNTFORD DEELEY, M. I. Mech. E., F.G.S. SECOND EDITION. Revised. Large 8vo. Cloth. Illustrated. "DESTINED TO BECOME A CLASSIC on the subject."-Industries and Iron.

ENGINE ROOM PRACTICE: By JOHN G. LIVERSIDGE, R.N., A.M.I.C.E. FOURTH IMPRESSION. Large Crown 8vo. With numerous Illustrations. 6s.

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VALVES AND VALVE GEARING: A Practical Text-book. By CHARLES HURST. FOURTH EDITION. Thoroughly Revised and greatly Enlarged. With several Folding Plates and numerous other Illustrations. 10s. 6d.

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BOILERS, LAND AND MARINE: Their Construction and Strength. By T. W. TRAILL, M.Inst.C.E., F.E.R.N., late Engineer Surveyor-in-Chief to the Board of Trade. THIRD EDITION. Revised and Enlarged. 12s. 6d.

"The MOST VALUABLE WORK on Boilers PUBLISHED IN ENGLAND."-Shipping World. THE HEAT EFFICIENCY OF STEAM BOILERS: Land, Marine, and Locomotive. By BRYAN DONKIN, M. Inst.C.E. In 4to. Handsome cloth. Numerous Illustrations. 258.

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ELECTRICITY METERS:

A Treatise

ON

THE GENERAL PRINCIPLES, CONSTRUCTION, AND TESTING
OF CONTINUOUS CURRENT AND ALTERNATING
CURRENT METERS, FOR THE USE OF

ELECTRICAL ENGINEERS

AND STUDENTS.

BY

george

HENRY G. SOLOMON,

ASSOCIATE MEMBER OF THE INSTITUTION OF ELECTRICAL ENGINEERS.

ENGIN. LIBRARY

TK
393

569

PREFACE.

ALTHOUGH the electricity meter forms the most important link in the chain connecting the supply station with the consumer, comparatively little has been written on the subject in this country. It is, therefore, hoped that the present work may supply what is wanting in this respect, and that some original matter may be found in the same, especially in connection with the limitations of three-wire meters, of single-phase meters for polyphase circuits, and the results obtained with polyphase meters incorrectly installed.

For the sake of convenience, the meters described in this book are divided into three main classes-viz., Continuous current, Induction, and Tariff meters-arranged in eight chapters, corresponding to the following eight subdivisions: Continuous current quantity meters: Continuous current energy motor meters (without iron in the field or armature): Continuous current energy meters of different types: Continuous current meters for special purposes (battery, switchboard, and tram-car meters): Single-phase and polyphase induction meters: Tariff and prepayment meters. The general principles involved are explained in three separate chapters, which precede the descriptions of the meters belonging to the three main classes as stated above.

As the proper working of a meter depends on its mechanical as well as its electrical design, a special chapter is added in which the more important mechanical features of meter construction are pointed out, only the electrical details being given in the actual descriptions of the various types. A chapter on Testing, and an introductory chapter containing a few remarks relating to meters in general, are also included.

After careful consideration, it was not deemed necessary to include an historical survey of the evolution of the electricity meter. The general design of electricity meters is at the present day fairly well established, the improvements being more a matter of detail and mainly of a mechanical nature, so that no purpose is served by giving descriptions of obsolete forms of meters, however ingenious their construction and interesting from a purely historical standpoint. With the exception of those meters which form the basis of present-day practice, the designs were on lines which are no longer followed.

The main difficulty in writing a book of this description is the well-nigh impossibility of keeping absolutely up to date. The author has, however,

endeavoured to embody, as far as possible, the latest improvements in the descriptions, and to include only those meters which are in commercial use in this country, on the Continent, and in America. It is not pretended that the list of such meters has been in any way exhausted, but it is trusted that a sufficient number of the more important types has been given to enable the reader to become conversant with the methods adopted to obtain a reliable and accurate commercial meter for different purposes.

No pains have been spared to make each chapter as comprehensive and complete as practicable within the scope of the book, and to separate the mathematical principles from the purely descriptive matter. The latter is not possible, however, in treating polyphase meters.

Special attention has been devoted to the detailed proofs of the power absorbed in a polyphase circuit, as it is not easy to deduce from the instantaneous values the form of the equation for the power absorbed when the values of the currents and pressures are those actually measured.

In conclusion, the author begs to thank the numerous manufacturers and engineers, both here and abroad, who kindly supplied him with information, drawings and blocks, and, in many cases, submitted samples of meters for inspection and testing.

H. G. SOLOMON.

5, VICTORIA STREET,

WESTMINSTER, S. W., January 1906.