Big Cottonwood Canyon powerhouse and transmission line

The Big Cottonwood Power Transmission

Before proceeding to a description of the recently completed electric transmission of the Big Cottonwood Power Company it is well to briefly review the natural advantages of the country contiguous to Salt Lake City in order that an accurate idea of the importance and far-reaching effect of the enterprise may be appreciated. It has been pointed out in an article by Mr. Geo. Heli Guy, in the Electrical Engineer, that cheap electric power for Salt Lake City and vicinity will open up unequalled opportunities for various electrical enterprises not only in the delivery of power for the operation of existing installations, but also for electro-chemical work. The district has bauxite in abundance, and in this industry power is all-important, and freight is hardly considered. For the manufacture of salt products, bleaching powder, disinfectants, soda, sodium, calcium carbide, etc., all the raw materials are on the ground, and cheap power only is needed. The electro-deposition of copper will certainly grow into a huge industry, for the extensive leads of copper ores are as yet undeveloped. A large cop per smelting plant has recently been placed in operation. The electro-deposition of gold and silver is also a coming industry which will rapidly expand when cheap current increases the economy of the process. These are classes of work depending for their successful prosecution almost entirely on power, and requiring materials mined or found in the Salt Lake country in enormous abundance. In mills and factories the ordinary industrial operations likely to be created by cheap power are wool scouring, paper making, the manufacture of cotton fabrics and the making of flour. With the increase in these factories there will be a call for better facilities for iron workers and engineering work, which will require further power. There will be a prompt and large demand for current for electric transit. Cheap power will enable trolley lines to be pushed out all over the Salt Lake Valley to be used for bringing farm produce into the city and ores to the smelters. With these improved facilities for transportation, the farming industry of the Salt Lake Valley will increase enormously, and a large fruit trade will be established. Three electric roads are already operating successfully; the Salt Lake City Railroad Company, the Salt Lake Rapid Transit Company and the West Side Rapid Transit Company, operating in the aggregate upward of 100 miles of track and about 100 cars. These roads already stretch out from 5 to 10 miles from the centre of the city. The output of gold and silver ore with lead bases is infinitely larger than statistics show, owing to the fact that enormous quantities of ore are shipped to Colorado smelters. Before long these ores will be smelted in Utah by electrical processes. The headquarters of the large mines, such as the Ontario, Centennial, Eureka, Mammoth, Anchor, Crescent, Silver King and the various mines in Park City, Tieutic, Bingham and Mercur, are all located in Salt Lake City. The first successful practical application of the cyanide process for extracting gold ores was made at the Mercur mines located within 10 miles of the city. There are four large smelters and five sampling works. These smelters and the mines require large quantities of power continuously through the year, and though the ap plication of electricity to mining is somewhat slow, it will surely become general. The Ontario mine has taken the lead by putting in a small monocyclic light and power plant, utilizing the water from the great drain tunnel.

The Big Cottonwood river forms the drainage of the Wahsatch range of the Rocky Mountains, lying immediately back of Salt Lake City, and the lakes entering into the Big Cottonwood canyon, lie at altitudes of from 11,000 to 13,000 feet above the sea, so that difference of level is considerable even when the water is made to give up its energy at a point some thirteen miles southeast of Salt Lake City. As a matter of fact, the company has available over 1,000 feet of fall in various spots, but at present is using less than 400. The power station, illustrated on page 22, is situated in the canyon at "The Stairs," about 14 miles by pole line from the distributing of "step-down" station of the Salt Lake and Ogden Gas and Electric Light Company, in Salt Lake City. At this point there is a minimum flow of 3,400 cubic feet per minute, which, working under 380 feet head, produces 2,447 horse power any and every hour in the year. During nine months of each year, it will give nearly 4,000 horse power. The frontispiece illustrates the storage reservoir at the head of "The Stairs," which has an available capacity of 24 hours' continuous flow of the stream, making all of the water available by using an excess during maximum loads and allowing the reservoir to accumulate during minimum loads. 58,800 horse power per day of 24 hours, is looked for from this source, of which 68 per cent. can be delivered in Salt Lake City in contract form, making 40,000 horse power hours net daily. The 68 per cent. efficiency is derived from: Pelton water wheels 80 per cent., General Electric Company generators 94 per cent. , G. E. transformers (raising) 97 per cent., line transmission 95 per cent., G. E. transformers (reducing) 973 per cent., or a total of 68 per cent. The map of the reservoir shows a pipe line extending from the head gates, submerged in the bottom of the reservoir, to a penstock or receiver wood housing with "grizzlies" located just below the bridge. This pipe, of steel-banded redwood, is anchored to the bottom by rock piles, and is to be used in the event of its being necessary to drain the reservoir, without interfering with the running of the station. This is accomplished by closing the headgate valves, and the station can thus be supplied from the natural flow of the stream, during such time as the reservoir might be empty. The steel pipe line was built by the Frazer & Chalmers Company of Chicago.

The outside dimensions of the generating station are 34 feet by 100 feet. The generating plant, a view of one half of which is shown on page 23, consists of four 450 kilowatt three-phase 60-cycle General Electric generators, separately excited, non-compounded, set with armatures parallel to each other, facing up in true line in the building. Each generator is driven directly by one heavy special Pelton wheel, 60 inches in diameter, provided with two nozzles of 3 in. diameter. The nozzles are provided with hood valves for shutting off, so that both good regulation and economical use of water are secured. Each nozzle at 370 feet effective head, produces 310 mechanical horse power, and drives the wheel at 300 revolutions per minute, its economical speed. The water wheel is keyed directly on the armature shaft, and in addition to the generators named, four 12 kilowatt exciters are connected together in pairs by coup lings, each set being driven by a 14-inch Pelton wheel, with cast housings. Each set consists of two generators and two wheels, built up on a cast-iron base-plate, making a rigid and direct connection. This application provides exciting energy in two units, and at all times either one or two exciters are in reserve. The exciters are to be run in multiple, and all connected to one common "bus line" on the switchboard. The three-phase generators are also operated in parallel. There are six raising transformers, 265 kilowatts each, of General Electric make.

The station switchboard consists of 5 panels with complete controlling and indicating apparatus, and there is a 3-panel raising transformer switchboard. At the step down or distributing station, there is a 3-panel reducing switchboard, with proper regulating apparatus. The apparatus is protected by ball lighting arresters, and the transformers are cooled by two Sturtevant exhaust fans driven by two 5-horse power induction motors.

The 915 poles for the line construction were selected from live growth of Sand Point (Idaho) cedar. The smallest are 40 feet long, and 8 inches in diameter at the top. They are placed 100 feet apart. The line conductors will consist of 12 wires, four circuits of three wires each, but only three such circuits are now in position. All wires are of No. 2, soft-drawn bare copper, and connected to the same common "bus line," at the generating and at the distributing station. The line loss, in delivering 1,520 kilowatts, at 10,000 volts, is something less than 5 per cent.

The transmission line from generating to distributing station is 14 miles by pole line. The distributing station is owned by the Salt Lake and Ogden Gas and Electric Light Co., who rent it to the Big Cottonwood Power Company at a nominal rent. It contains, for "step-down" transformation, nine 160 kilowatt air blast transformers, from the secondary side of which the Electric Light Company buys the current wholesale by meter. This arrangement is a most convenient one for both companies. The actual terms of the contract are that the electric light company is to be supplied with all the current it can dispose of for electric lighting and power, in units of 10 horse power, and under, the Big Cottonwood Company reserving the right to supply power to motors in units exceeding 10 horse power, and the right to reach such wholesale users of power by wires erected on the electric light company's poles, throughout all the districts within the city limits. The contract dates from January 1, 1896, and runs for a term of five years. Its conditions are that the current is bought at 2,000 volts, 3-phase, at a stipulated price per k. w. hour, which will be used to supply electric light and power for any purpose up to 10 horse power, and for elevator service up to any limit desired by the lessees . 2,000,000 units annually is the minimum limit of the consumption of current.

The final cost of the complete development is estimated at $300,000. An estimate of $300,000 for the original outlay for "The Stairs" would give for construction expenses at 2.258 horse-power-$132.72 per net horse-power de- livered in the city ready for use. The future of the company seems to be well assured. The company's affairs have been so well administered that much more than half the power to be developed has already been disposed of absolutely, and the guaranteed total revenue from completed contracts is over $100,000 annually. Although the company is confining its operations for the present to "The Stairs" supply, it has, as already stated, other valuable water rights partly developed by means of which it could at any time largely supplement its output.

In order to secure the best results from the three-phase current the Salt Lake Gas and Electric Company, originally a single-phase plant, has modified its distribution system. The new system consists of a network of primary mains with a network of low tension secondaries, wherever the houses are in close proximity to each other. The primary mains are at 2,000 volts. They run along every street east and west and have equalizing cross mains on several streets running north and south. There will eventually be ten feeding points, though at first only six are required. Secondary mains are used almost entirely; only when the houses are very scattered separate house transformers are used.

In the commercial district, the secondary and primary mains will eventually be put underground, though this is not immediately contemplated. The transformers are placed at street intersections in banks either fixed on poles or in any suitable location near the intersection. In the commercial districts there will be a bank of transformers at every street intersection; but in the incidental districts one bank will be placed at every other intersection, the blocks being 792 feet square. The feeders are brought from the distributing station situated near the center of the town. The current is supplied from the generators of the Big Cottonwood Power Company's station on the three phase system. The feeders and primary mains therefore consist of three wires each of the same size. The secondary mains consist of three wires and a neutral wire. The volt age between any one of the three wires and the neutral is 115, and this is the voltage of the lamps. Motors, synchronous or non-synchronous, can be connected at any point to the secondary mains, or, when the motor is large, separate transformers will be used. It is intended to eventually use the alternating current for all are lamps, in which case they will be connected to the secondary mains with small transformers. At present the arc lighting of the city is done by constant current generators driven by three-phase synchronous motors in the old steam power house of the Salt Lake Gas and Electric Company. The distributing station is a substantial fire proof building, with a room for the 10,000-volt step-down transformers, the 2,000-volt switchboard and fitted up with instruments for testing and calibrating meters, etc.

The distributing system and feeders have been designed of ample capacity for a small drop, and with the complete system of primary and secondary mains the regulation is perfect. By cutting out transformers during times of light load, it is expected to obtain a very high distribution efficiency. The Stairs plant of the company was completed in time to deliver current in Salt Lake City by June 1. A few days after, the greatest flood seen in thirty-five years rushed through the canyon, thus testing in the severest manner the strength of the construction. Not a dollar's worth of damage was done.

The officers of the Big Cottonwood Power Company are John W. Donnellan, president (cashier Commercial National Bank, Salt Lake); W. H. Rowe, vice-president, (president Bear River Canal Company); Geo. M. Cannon, secretary (cashiers, Zion's Savings Bank, Salt Lake); G. M. Downey, treasurer (president Commercial National Bank, Salt Lake) ; R. M. Jones, engineer and manager, Salt Lake; Jos. W. Summerhays, director, Salt Lake. The Old Colony Trust Company, of Boston, is its trustee.

At the present time, The Stairs plant, at ruling rates for current, can earn $200,000 per annum, and it would seem that a ready market exists for light and power now, some 27 concerns using over 2,000 horse-power. Many of these establishments work every day the entire year, and their steam power has cost them from $90 to $145 power per year per horse

These works have involved an outlay of something over $300,000, all of which has been furnished by local capitalists. The company states that contracts for power have already been made, which afford a revenue of $100,000 per year with a very considerable surplus of power yet to be disposed of, which insures a dividend of not less than 20 per cent. per annum over and above interest and operating expenses.

The financial as well as engineering success that has at tended most enterprises of this character in various parts of the country, has given assurance of safe and profitable returns to all such investments where planned with proper reference to cost of installation and commercial value of power produced.