Fig. 279 - Location of spark-gap dischargers for various arrangements of transformers.
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The 'Preface' states:
This volume contains a collection of circuit diagrams, representing more or less completely all branches of electrical engineering, with the exception of telephony and telegraphy. [...] The circuit connections are drawn so as to be self-explanatory, thus reducing the necessary text to a minimum.
(Additional information from this book is located on the History of Electrical Systems and Cables page.)
The following information is excerpted from this book.
[...]
Fig. 279 - Location of spark-gap dischargers for various arrangements of transformers.
[...]
The 'Preface' states:
This book had its origin as part of a training program for the mechanical workers and technicians newly employed by an electric utility. With time, its contents have been expanded and revised periodically to reflect changing scopes and technology, yet keeping in mind that the use of existing equipment and practices will persist until economic obsolesence. [...] Many of the illustrations have been culled from publications, catalogs, training manuals, operating and maintenance instructions of equipment suppliers, and from industry, trade, and related literature, including utility standards and specifications. Among the major contributors were the General Electric Company, Westinghouse Electric Company, McGraw Edison Company, James G. Biddle Company, and the Long Island Lighting Company.
The following information is excerpted from this book.
Introduction: The Transformer
The invention of the transformer in 1884, overcoming the technical and economic limitations associated with the original dc (direct current) commercial system, made practical the eventual availability of electric power to almost every home, farm, office, store, and factory. The commercial ac (alternating current) distribution system using transformers was put in operation two years later in Great Barrington, Mass. In the same year, 1886, ac power was transmitted at 2000 volts over 30 kilometers of line built at Cerchi, Italy. From these small beginnings, the electric power industry has grown to the giant, almost universal, force for the good of mankind the world has ever seen. For all practical purposes, this industry today is entirely a supplier of alternating current; and its development is entirely due to the transformer.
Figure 1-1, showing typical facilities required to supply electric service, vividly indicates the many places in the supply system where transformers are used.
[fig1-1 p4]
The transformer is a device, having no moving parts, which transfers electric power from one circuit to another by electromagnetic means, usually with changes in values of both voltage and current. A step-up transformer receives electrical power at one voltage and delivers it at a higher voltage; conversely, a step-down transformer receives electrical power at one voltage, and delivers it at a lower voltage. [...]
The transformer is a highly efficient device, so that practically the full electrical power received from one circuit is delivered to the other. Since electrical power (P) may be considered the product of voltage (E) and current (I) (that is, P = E x I ), it is evident that the values of current in a transformer change in opposite faction to those of the voltage. That is, in a step-up transformer where the voltage delivered is higher than that received, the current delivered is lower than that received; in a step-down transformer, where the voltage delivered is lower than that received, the current delivered is higher than that received.
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