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Page 889 | Volume 3 | Chapter 43 | Lightning Protection

one plate to the other thus quickly destroying the plates and causing other more serious damage.

Ques. What provision is made to prevent the destruction of arresters by the line current?

Ans. Lightning arresters used on heavy duty circuits are designed to rupture the arc as soon as formed.

Fig. 1,042. - Diagram showing operation of variable gap arc breaker used on heavy duty lightning arresters.
Fig. 1,042.—Diagram showing operation of variable gap arc breaker used on heavy duty lightning arresters. When a lightning discharge passes across the gap to earth, the dynamo current follows it and energizes the magnet M, which attracts the short arm of the double lever, thus quickly jerking the terminal B away from C. The wider air gap thus interposed between B and C greatly increases the resistance which breaks the arc.

Ques. How is this done?

Ans. There are several methods, of which may be mentioned the variable gap method described in fig. 1,042, and the magnetic blowout method shown in fig. 1,043.

Ques. Where should lightning arresters be placed?

Ans. They should be placed as near as possible to the point where wires enter a building, and in an easily accessible place away from combustible material.


What is the Hawkins Electrical Guide?

When first published in 1914, these books were intended to explain the scientific principles of electricity (which at the time was a new and exciting technology) with "the aid of a very large number of illustrations, together with specific explanations, worded in concise and simple language".

What really makes this collection of books special today is the detailed documentation of most of the earliest inventions in electrical history including telegraphs, motors, switchboards, and high power distribution systems.

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Unfortunately, priceless material like this usually finds itself in the lost history of America. The mission of this project is to preserve that history and provide a simple yet powerful, direct means to each volume in digital form in which anyone can access while keeping as true to the original format as possible.

The project was started in July 2012 and is currently still in the developmental stages. It is projected that it could take 12+ months to get all of the material up. The good news is it's being added in order so users can begin reading while the latter material is being added. Until now, the only means of access to this material online were a few PDF, static html, and plain text versions from Google Books and Project Gutenberg.

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  • 10.29.2013 - Moved to new servers and uploaded Chapter 49: Alternators.
  • 3.1.2013 - Uploaded Chapter 47: Alternating Current Diagrams, and Chapter 48: The Power Factor.
  • 2.20.2013 - Uploaded Chapter 46: Alternating Currents
  • 12.29.2012 - Uploaded Chapters 44 and 45, check out storage battery principles and systems. This addition completes volume 3.
  • 12.23.2012 - Uploaded Chapters 42 and 43, check out sign flashers and lightning protection.
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