Other Early Stations--The Meter - 3

Other Early Stations--The Meter - 3

 It is needless to say that in due course the engine builders of the United States developed

a variety of excellent prime movers for electric-light and power plants, and were grateful

to the art from which such a stimulus came to their industry; but for many years one

never saw an Edison installation without expecting to find one or more Armington &

Sims high- speed engines part of it. Though the type has gone out of existence, like so

many other things that are useful in their day and generation, it was once a very vital part

of the art, and one more illustration of that intimate manner in which the advances in

different fields of progress interact and co-operate.

Edison had installed his historic first great central- station system in New York on the

multiple arc system covered by his feeder and main invention, which resulted in a notable

saving in the cost of conductors as against a straight two-wire system throughout of the

"tree" kind. He soon foresaw that still greater economy would be necessary for

commercial success not alone for the larger territory opening, but for the compact

districts of large cities. Being firmly convinced that there was a way out, he pushed aside

a mass of other work, and settled down to this problem, with the result that on November

20, 1882, only two months after current had been sent out from Pearl Street, he executed

an application for a patent covering what is now known as the "three-wire system." It has

been universally recognized as one of the most valuable inventions in the history of the

lighting art.[13] Its use resulted in a saving of over 60 per cent. of copper in conductors,

figured on the most favorable basis previously known, inclusive of those calculated under

his own feeder and main system. Such economy of outlay being effected in one of the

heaviest items of expense in central-station construction, it was now made possible to

establish plants in towns where the large investment would otherwise have been quite

prohibitive. The invention is in universal use today, alike for direct and for alternating

current, and as well in the equipment of large buildings as in the distribution system of

the most extensive central-station networks. One cannot imagine the art without it.

[13] For technical description and illustration of this invention, see Appendix.

The strong position held by the Edison system, under the strenuous competition that was

already springing up, was enormously improved by the introduction of the three-wire

system; and it gave an immediate impetus to incandescent lighting. Desiring to put this

new system into practical use promptly, and receiving applications for licenses from all

over the country, Edison selected Brockton, Massachusetts, and Sunbury, Pennsylvania,

as the two towns for the trial. Of these two Brockton required the larger plant, but with

the conductors placed underground. It was the first to complete its arrangements and

close its contract. Mr. Henry Villard, it will be remembered, had married the daughter of

Garrison, the famous abolitionist, and it was through his relationship with the Garrison

family that Brockton came to have the honor of exemplifying so soon the principles of an

entirely new art. Sunbury, however, was a much smaller installation, employed overhead

conductors, and hence was the first to "cross the tape." It was specially suited for a trial

plant also, in the early days when a yield of six or eight lamps to the horse-power was

considered subject for congratulation. The town being situated in the coal region of

Pennsylvania, good coal could then be obtained there at seventy-five cents a ton.

The Sunbury generating plant consisted of an Armington & Sims engine driving two

small Edison dynamos having a total capacity of about four hundred lamps of 16 c.p. The

indicating instruments were of the crudest construction, consisting of two voltmeters

connected by "pressure wires" to the centre of electrical distribution. One ammeter, for

measuring the quantity of current output, was interpolated in the "neutral bus" or thirdwire

return circuit to indicate when the load on the two machines was out of balance. The

circuits were opened and closed by means of about half a dozen roughly made plugswitches.[

14] The "bus-bars" to receive the current from the dynamos were made of No.

000 copper line wire, straightened out and fastened to the wooden sheathing of the station

by iron staples without any presence to insulation. Commenting upon this Mr. W. S.

Andrews, detailed from the central staff, says: "The interior winding of the Sunbury

station, including the running of two three-wire feeders the entire length of the building

from back to front, the wiring up of the dynamos and switchboard and all instruments,

together with bus-bars, etc.--in fact, all labor and material used in the electrical wiring

installation--amounted to the sum of $90. I received a rather sharp letter from the New

York office expostulating for this EXTRAVAGANT EXPENDITURE, and stating that

great economy must be observed in future!" The street conductors were of the overhead

pole-line construction, and were installed by the construction company that had been

organized by Edison to build and equip central stations. A special type of street pole had

been devised by him for the three-wire system.