WeRead Powered by ReaderPub
History of electric light cover

History of electric light

Chapter 31: OTHER AMERICAN ARC LIGHT SYSTEMS
By Henry Schroeder
Open in WeRead

Explore more books like this:

Engineering & TechnologyHistory - Modern (1750+)

About This Book

A chronological, technical survey of electric lighting traces developments from early experiments with friction machines, Leyden jars and voltaic piles through advances in batteries, electromagnetic discoveries and the invention of the dynamo. It follows the parallel evolution of arc and incandescent illumination, outlining experimental filament and arc-control methods and the move to commercial installations and distribution schemes such as series, multiple and three‑wire systems. Later sections review later lamp technologies—Nernst, mercury‑vapor, gas‑filled and tungsten types—together with transformers, rectifiers, standardized voltages and sockets. The book is illustrated and includes a chronology, cost and usage statistics, and a selected bibliography.

OTHER AMERICAN ARC LIGHT SYSTEMS

Thomson-Houston Arc Lamp, 1878.

This is an early model with a single pair of carbons.

Thomson Double Carbon Arc Lamp.

This later model, having two pairs of carbons, was commercially used for many years. This lamp is in the collection of the Smithsonian Institution.

Beginning with about 1880, several arc light systems were developed. Among these were the Vanderpoele, Hochausen, Waterhouse, Maxim, Schuyler and Wood. The direct current carbon arc is inherently more efficient than the alternating current lamp, owing to the fact that the continuous flow of current in one direction maintains on the positive carbon a larger crater at the vaporizing point of carbon. This source furnishes the largest proportion of light, the smaller crater in the negative carbon much less. With the alternating current arc, the large crater is formed first on the upper and then on the lower carbon. On account of the cooling between alternations, the mean temperature falls below the vaporizing point of carbon, thus accounting for the lower efficiency of the alternating current arc.

Maxim Dynamo.

This dynamo is in the collection of the Smithsonian Institution.

For this reason all these systems used direct current and the 10 ampere ultimately displaced the 20 ampere system. The 10 ampere circuit was later standardized at 9.6 amperes, 50 volts per lamp. The lamp therefore consumed 480 watts giving an efficiency of about 15 lumens per watt. This lamp gave an average of 575 candlepower (spherical) in all directions, though it was called the 2000 cp (candlepower) arc as under the best possible conditions it could give this candlepower in one direction. Later a 6.6 ampere arc was developed. This was called the “1200 cp” lamp and was not quite as efficient as the 9.6 ampere lamp.