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burdensome. I know many companies do not join it because of that one fact alone; and this organization would be very much stronger and much better able to accomplish what it wants to accomplish if it had a membership of 500 illuminating companies all over the United States, instead of the paltry 100 that we have. That is certainly not creditable for a national association.

As the chairman has seen fit to refer as he has to the Edison association, I might say that association has strictly confined its membership to those actively employed in the business of those companies. It was organized for that purpose, and confined to a very limited number. You know how limited the number of Edison licenses is; we have some sixty members. These sixty members by their contributions have maintained that organization now for ten years. This organization, being a national one, intended to embody all the state organizations, the Edison associations, and other associations allied to certain

types of apparatus,-should have at least 500

members. It should be the source from which the state institutions draw their inspiration and their ideas as to procedure in the various states. And that is the whole purpose of my remarks-for the work that the local companies need its assistance in. This is not my first appearance here; I paid my dues once before. I saw very little business transacted that was of value to the companies, and I dropped out. I am just at present located in Cincinnati, and concluded to attend this session and see whether the changes suggested as having taken place were being realized. I wish to state that I intend no reflection at all upon the honesty of any one. It is certainly apparent from the statement of the chairman that up


to the time he referred to the association had not been well managed, but was $3,000 in debt. I have no doubt that that period has been passed, as it undoubtedly has been, as shown by the report. should like to take an active part in the proceedings of this association, but I will state here that it will always be in behalf of the local illuminating companies.

THE PRESIDENT: We will close this discussion, and bring it up in the executive session when the report of the secretary and treasurer comes up for consideration.

THE PRESIDENT: We will now listen to a paper by Mr. W. E. Harrington, on "The Correct Method of Protecting Electric Circuits."

Mr. Harrington then read his paper as follows: CORRECT METHOD OF PROTECTING ELECTRIC CIRCUITS.

Mr. President and Gentlemen of the National Electric Light Association: The use of fuses for the protection of electric circuits has proved unreliable and unsatisfactory. The adoption of magnetic circuitbreakers being, as it is, a foregone conclusion, led the writer to make a study into the requirements entering into what would constitute a technically correct form of magnetic circuit-breaker.

In a circuit entirely or partially inductive, a sudden increase of current is checked by the impedance of the inductive part of the circuit. The rise in current, with the time, is illustrated by curve No. 1 taken from Bedell & Crehore's work on alternating currents.

This curve gives the rise in current, with time, in a circuit whose resistance is 1 ohm and coefficient of self-induction is .or henry.

The curve is based on Helmholtz's formula

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L = Coefficient of self-induction in henrys.

This is a logarithmic curve, and from the character of the formula, which is an exponential function, the practical interpretation has very seldom been appreciated by the practical operators of electrical apparatus. The utilization of the principle embodied in Helmholtz's formula gives the solution to the problem to determine the correct method of protecting electric circuits. The use of fuses for the protection of circuits has proved. to be so antipodal to the fundamental principle contained in what is the severely technically correct method,

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that it is criminal, almost, in the light of present practice, for users to follow like sheep in the path of their predecessors in the use of fuses. The practical interpretation of the above formula indicates clearly that if a circuit be opened during the rise or first surge in current upon a tendency for abnormal flow, and further, if the time of opening be made as quickly as possible, the less the resulting flow of current will be. To realize the importance of this time element in the opening of a circuit, if we refer to curve No. 1, it

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is apparent that if the circuit were opened in of a second, the current would be only one-half the strength it would be if allowed to flow until it had reached the volume due to ohmic resistance alone.

It will also be noticed that if the circuit were opened in of a second, the current would be about one-sixth its final value.


To eliminate mathematics, and that most elusive



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of all electrical units to grasp, the henry, and to illustrate in every-day amperes the effect time has upon opening a circuit in a working power station, wherein exists the self-induction of the dynamos and station appliances, and the small negligible selfinduction of the measuring instruments used in testing -tests were made in the power station of the Camden Horse Railroad Company as follows:

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