Publication: American Institute Of Electrical Engineers
New York, NY, United States
THE TRANSMISSION PLANT OF THE NIAGARA, LOCKPORT AND ONTARIO POWER COMPANY
BY RALPH D. MERSHON
On the seventh day of July, 1906, there was put into operation the first of the transmission lines of the Niagara, Lockport and Ontario Power Company. This event marks the inauguration of one of the first undertakings in the matter of distributing Niagara power over a large section of country, and the beginning of an enterprise which is one of the most important, and in some respects the most important, of its kind anywhere in the world.
The plans realized at present and contemplated for the immediate future, in the plant of the Niagara, Lockport and Ontario Power Company, involve a maximum transmission distance of 160 miles. This distance puts the plant amongst the longest transmissions of the world. As regards capacity, the plant of the Niagara, Lockport and Ontario Power Company is now one of the most important in existence, and, in the near future, its capacity will be far in excess of any other transmission system in the world. In addition to these points of importance, there are a number of engineering features somewhat out of the usual line of transmission practice which make the installation of interest from an engineering standpoint. Inasmuch as the description of such a plant is usually more satisfactorily accomplished through pictures than otherwise, they will be mainly resorted to herein, with the aid of only such brief text as may be necessary to cover points which cannot be well shown in illustrations.
The prospective system of the Niagara, Lockport and Ontario Power Company is a comprehensive one for the delivery of power in the United States within an economic transmission radius of Niagara Falls, and especially for its delivery in the northern and western portions of the state of New York. The company expects within the next two years to be transmitting 60,000 horse power, and its present right-of-way purchases are with reference to an ultimate transmission of 180,000 horse power. The plans of the company as at present laid out contemplate the transmission of this power by means of main lines and branch lines therefrom; the contracts for power being, wherever possible, made for delivery of the power at the main-line voltage of 60,000, less line drop. Where, however, the business of a given territory will justify it, the company will install step-down transformer stations for the delivery of power at a lower voltage. Each of the main transmission circuits will be capable of receiving and transmitting 30,000 horse power at 60,000 volts, and it is intended always to provide a sufficient number of spare main transmission lines to insure continuity of service on the main line. Spare lines will be provided in the case of branch lines only when the latter are of considerable importance.
The Niagara, Lockport and Ontario Power Company is only a transmission company; that is, it buys the power to be transmitted and has, therefore, no generating plant of its own. The power for the transmission is generated in the hydraulic power station of the Ontario Power Company, situated on the Canadian side of Niagara Falls. The water for this station is taken from the Niagara River, some distance above the falls, whence it is brought to a point at the top of the cliff, a short distance below the falls, through underground steel conduits, and from this point delivered through underground penstocks to the power station located at the bottom of the cliff, near the foot of the falls.
The power house contains the generating units with their exciters and switchboard apparatus. The generators have a capacity of 7,500 kw. each, and deliver three-phase 25-cycle current at 12,000 volts. From the power station the current is taken at 12,000 volts to the transforming and switching station of the Ontario Power Company located on the bluff above the falls. It is stepped up from 12,000 volts to 62,500 volts, and at this latter voltage delivered to the transmission lines. The transmission lines of the Ontario Power Company extend from its transforming station to a point some six miles farther down the Niagara River, at which point the lines connect to circuits spanning the Niagara River. The Niagara, Lockport and Ontario Power Company takes delivery of the electric power at the international boundary line in the middle of the Niagara River.
At the present time, the Niagara, Lockport and Ontario Power Company has in its possession a private right-of-way 300 feet wide from the Niagara River to the town of Lockport, about 16 miles east; from Lockport east to Mortimer (six miles south of Rochester) a private right-of-way 200 feet wide, a distance of about 57 miles, from Mortimer to Fairport a 100-foot private right of-way a distance of 10 miles; and from Fairport to Syracuse a private right-of-way 75 feet wide, a distance of 71 miles. From Lockport south in the direction of Buffalo, the company has a private right-of-way 100 feet wide. In addition to this, the company has the right to install transmission lines on the right-of-way of the West Shore Railroad and has acquired the necessary private right-of-way to get from its main private right-of-way to that of the railroad company.
The installation which the company has now in operation is for receiving 30,000 horse power and delivering this amount, less the line loss. The main transmission consists of two lines in duplicate. From the Niagara River to Lockport, a distance of 16 miles, there are two lines on the company's private right-of-way, each capable of transmitting 30,000 horse power. From Lockport to Mortimer, a distance of 57 miles, there is a line on the company's private right-of-way having a capacity of 20,000 horse power. From Mortimer east to Syracuse, a distance of 81 miles, there is a line on the company's right-of-way
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secured to the poles by braces. On each end of each pair of poles was spiked a box, built up of planking and filled with stone, in order to give sufficient weight to take the uplift due to any pull at the top of the tower. This structure, while far from beautiful, has, so far, proved very satisfactory. The tower construction and the A-frame construction in swamps are shown in the illustrations.
It will be noted that, in some of the illustrations of the towers and A-frames, there is shown a horn attached to a cap on the top of the insulator and another horn alongside of it fastened to the structure and extending some distance above the insulator. This comprises a combined line-structure lightning-arrester, or spark-gap, and lightning-rod. It has been decided to make a careful trial of this method of protection of the line before resorting to a grounded cable; partly because of the great expense of the grounded cable, and partly because there is no reason to think, so far, that it will necessarily afford complete protection in every case. For the present, these line- structure lightning-arresters will be installed only on the top cable, in view of the fact that during the last lightning season, in the course of which a number of insulators were broken by lightning, more than three-fourths of the insulators so broken were top insulators.
The insulator used on all the main-line construction is one especially designed for this plant by the writer. It has probably the greatest factor of safety as regards flashing, etc., of any insulator in practical use to-day, and is considerably larger and heavier than any insulator of which corresponding use has heretofore been made. It consists of three shells nesting in one another and cemented together by means of neat Portland cement, the whole insulator being cemented in a similar manner to a steel pin before attachment to the tower. The insulator is clearly shown in one of the illustrations. The total height of it from the edge of the lower petticoat to the top of the head is 19 inches. The diameter of the upper petticoat is 14.5 inches. The insulator used on some of the branch lines is smaller and less expensive than that for the main line, partly because the branch lines receive in general a somewhat lower voltage than the main line and partly because the lines, carrying the small amounts of power they do, are not considered to be entitled to the same insurance as the main line. Each branch line has in series with it, at the point where it is tapped off the main line, 60,000-volt outdoor fuses to cut out the line in case of trouble on it. The fuses consist of lengths of thin copper wire 16 feet long, run through an ordinary small rubber bathroom hose and laid in clips on top of a wooden bar supported at each end and at the center by line insulators mounted on poles.
The fuses are parallel to each other in the same horizontal plane, and the distance from center to center is about 25 feet. These fuses have so far proved very satisfactory but will probably in time be replaced with fuses of the explosion type. The outdoor 60,000-volt fuses are shown in one of the illustrations.
There are only three sizes of cables used on the main transmission line, designated by the company as 3/3, 2/3, and 1/3 respectively. The 3/3 cable is aluminum cable, consisting of 19 strands, and having a total area of 642,800 cir. mils, being equivalent to 400,000 cir. mils copper. The areas of cross-section of the other cables are respectively two-thirds and one-third that of the large one.
In ordinary straight-away work, the cable lies in the top groove of the insulator, and the pull of the cable is taken care of by means of two aluminum wire ties around the neck of the insulator. One of these ties extends each way along the cable. The tie itself consists of a single loop around the neck of the insulator, the two ends of the loop being twisted around the line cable. The result is that the cable is not really fastened to the insulator at all, but simply lies in the top groove. The ties do not, therefore, perform any function, except when there is a pull on the cable tending to slide it in the direction of its length. The advantages of such a tie are twofold. first, the full strength of the tie wire is developed. which is not the case if a tie is twisted or "pig-tailed," since in such case the tendency is for the tie to cut itself in two at the twist; secondly, the tie does not damage the soft aluminum cable, as would be the case with most of the other ties usually employed.