Publication: The Journal of Electricity, Power and Gas
San Francisco, CA, United States
most pronounced in winter when insulators, pins, cross arms and poles became soaked with water and electrical breakdowns became inevitable. All would have been well had even the insulator alone remained dry, but the dripping of water from its exposed portions, and the seepage along its under surfaces gave rise to electrical leakages that were the sure forerunners of trouble. But finally some one in the laboratory of the Stanley Electric Manufacturing Company at Pittsfield, Mass., suggested that possibly the condition might be improved if a rim be placed around the edge of the top piece of the insulator, so that the rain would be collected, and run off as a solid stream through a spout. This was done, and while, of course, an ordinary manner when the insulator was subject to no electrical pressure, the water was scattered outwardly as a spray when it was subjected to a high potential charge. The accompanying halftones, reproduced from photographs taken by Mr. E. E. Stark, illustrate the effect very prettily. A Locke insulator, such as that used on the Bay Counties' high tension lines, was mounted on a pin and cross arm after the customary manner, and a leaking tin can, placed on its top, gave improvised rain. The first engraving shows how the water falls in a solid stream when no electrical potential is on the insulator; the second shows how the same stream is scattered when a potential of 40,000 volts is applied to the insulator — scattered because the particles of water have each become electrified to a like polarity, and "like electricities repel." As a result, the under portions of the insulators are always dry and transmission at extremely high potentials becomes an assured and successful reality.
But to resume our story, the other road referred to as leaving Dobbins goes past Lake Frances — the company's principal reservoir, and on down to Colgate, whence the transmission lines radiate to the east and the west to the various points of service. One of these lines, which is of aluminum, stranded like a rope, and barely 1/4-inch in diameter, goes to Sacramento, sixty-one miles distant, and over this line energy to the amount of 3000 horsepower may be transmitted whenever desired at a pressure of 40,000 volts. Another similar line radiates in a northwesterly direction to Oroville, some thirty miles away, where power is delivered to two sub-stations and thence distributed over many miles of territory, for use principally in the operation of the famous gold dredgers of the Feather river district. It is exceedingly interesting to watch these huge machines in their work of reclaiming gold from the gravel and soil of both ancient and present river beds. Originally the dredgers were built to operate in river channels alone, but now the application of them has been carried to the seemingly absurd point of digging a great hole in an orchard, filling it with water, building a thoroughly seaworthy ship of a capacity of several hundred tons, launching it into this artificial mud-hole, and then together, the mud-hole and dredger work their way through lowlands, leaving behind as ashes of devastation, an unbroken trail of gravel. Every function of the operation of these dredgers is performed by electricity, from the making of artificial light to the hoisting of dippers, and the running of link buckets, pumps, shakers, gypsies, capstans, stackers and, in fact, everything. At present something more than moo horsepower is consumed in dredging operations in the Feather river district, and in view of the number of new dredgers which are under contract to be built along the Feather river during the present season, it is safe to say that within a year the consumption of power in this direction alone will more than triple the present business.
Other lines radiating in a westerly direction from the Colgate power house are the Marysville and Brown's Valley circuits, which also afford the connecting link for tying together the Colgate and old Yuba power houses. These lines are run at 16,000 volts and are of aluminum. In addition to these are two new pole lines also running out in a westerly direction from Colgate, each of which carries three wires to the region in and about the bay of San Francisco —these are the world-famed Bay Counties' transmission lines, of which more will be said later. Climbing the almost precipitous sides of the canyon opposite the Colgate power house, is the pole line which carries power to the Nevada county's generating station on the South Yuba river, near Nevada City, some seven miles from Colgate, and over which 1000 horsepower or thereabouts is being continuously transmitted day and night at a pressure of 23,000 volts.
All these poles, and all these lines running out from Colgate present a scene that is probably without a parallel in the world. Coming down the hill from Dobbins after leaving Lake Frances, one sees the power lines before he does the power house, and their appearance is such that, with the aluminum sheening like silver thread in the sunlight, one could almost believe that some giant spider had begun to weave its web, for with the "parlor" down there somewhere on the river side the ribs of the web radiate out across canyons and over mountains until lost in the sky lines. To be accurate there are forty-one of these lines, while the poles supporting them form a forest which, from some points of view, seems to be a very dense one. These are the main high tension pole lines and their aggregate length exceeds 500 miles, while the length of the line wires, high tension and otherwise, constituting the entire system materially exceeds 3000 miles, as has been stated heretofore.
Lake Frances has been referred to only incidentally, but in reality it constitutes a feature that, from an engineering standpoint, is very interesting. To understand it the layman should know that the amount of water applied to the water wheels in an electric power transmission plant will vary directly with the amount of electricity that the dynamos therein may be called upon to deliver; consequently when an electric car starts in Oakland, for instance, the automatic governing devices upon the water wheels in the Colgate power house, 132 miles away, instantly respond to the added burden thrown upon the dynamos by applying just enough more water to the water wheels to supply the power which the car demands in starting. The flow of water in a pipe line operating under a high head can not be stopped suddenly as one does a faucet, because the momentum of water in the pipe would burst it, hence the only way to solve the problem is to divert the stream on to or away from the buckets of the water wheel as more or less power may be demanded from the dynamos. It is for this reason that such great streams of water are seen shooting out from under the Colgate power house, clear across the river. The power of these giant streams from the tail races is not used in any way, for with the taking of power from the stream of water, its velocity is destroyed and converted into energy, while the water itself runs idly out of the wheel pit. When the dynamos are running to full load, that is, to their full capacity, a cataract of water falls from each wheel pit over the rocks into the river below, but there is no stream shooting across the river.
These points have been gone into thus fully that the reader may understand the fact that there is always margin, more or less wide, existing between the maximum working capacity of an electric power house and the amount of the work which it actually does, and also Ural this margin must be wider when the work which the power house actually does depends upon service such as electric lighting, which is rendered only by night or for portion of the time, The reader will also understand therefrom that in order to supply great demands upon it the electric station must always have sufficient reserve capacity in its machinery to meet any sudden calls for power, and further that this reserve capacity, although it must always be ready for use, will be but infrequently called upon for maximum service.
The existence of Lake Frances, which is the safeguard of the water supply in that it assures its permanency, is due mainly as a result of the conditions which have just been set forth. True, it is filled by Dobbin's creek during winter months, but Dobbin's creek will not maintain Lake Frances with its full storage of water, amounting to nearly 93,000,000 cubic feet, all the year round, so some of the surplus power from the power house is to be used to keep the reservoir full of water. In other words, the power house is to run part of the time on water that it has itself pumped into the reservoir. It is planned that it shall be done this way: Centrifugal pumps, run by electric motors, which are in turn driven by electric power from the dynamos when the latter are not fully loaded, take water from the flume and pump it through a line of wrought steel and wood stave pipe, some two miles in length, to Lake Frances. The electric motors and pumps are to be located in a little pumping station near the lower end of the flume, and an interesting point in the installation lies in the fact that inasmuch as Lake Frances is a an altitude of 382 feet above the flume, it becomes a very simple matter to run the water from Lake Frances into the flume through water wheels that will drive as dynamos the electric motors which are connected to the pumps, and so give that much more energy to assist the large dynamos in the main station in carrying the load. In reality an electric motor, a centrifugal pump, and a water wheel have their shafts all connected together in one line so that when the electric motor is being driven by power from the main dynamos in the Colgate power house, the water wheel is shut off and the centrifugal pump forces water, taken from the flume, into Lake Frances. On the other hand, when the Colgate power house takes water from Lake Frances, the centrifugal pump is shut off, as is also the electric power from the motor at the pumping station ; the water taken from Lake Frances is thrown first upon the water wheels at the pumping station, whence it goes into the pipe lines to the main power house and the power developed by the water wheel at the pumping station is applied directly to the electric motor with which it is connected, whereupon the motor becomes a dynamo and delivers electric power to the general system.
This very ingenious method not only insures permanence of the water supply for the main power house, but also actually enables the company to get more power out of its water than it would do if the entire energy of the water were utilized at the main power house, without incurring the waste due to running the dynamos at less than full load. The idea savors of lifting one's self by the boot straps, but it is as practicable as it is ingenious.
Geographically, Colgate is located nearly in the center of Yuba county, at an altitude of 600 feet above sea level. It is entirely closed in by mountains that rise probably 1200 feet higher, so that it forms a community isolated by itself, so far as being on a public or even semi-public thoroughfare is concerned. The employees of the company are well provided for, however, for it has built the commodious "Hotel Martin," that is new and thoroughly modern in every respect, even to an ice machine. This latter reference recalls the stock joke among the employees of the company that the builders of the ice machine, in shipping it out to this "wild, wooly, and unbeknighted" country took the precaution to send a barrel of brine out with it, clear across the continent at high cost in freight charges, lest presumably those people who have beaten the world in the application of electricity in the transmission of power, might not know how to mix salt and water.
Of the hundreds of photographs which have been taken of features of the Bay Counties' system, probably none are more unique than the adjoining ones. Some wag has referred to the picture as representing "Byron crossing the Hellespont, a la Dante." The fact is that Byron was a favorite bird dog, whose master had come over to the Colgate power house on the "flying dutchman," leaving the dog behind on the opposite shore. The river was too swift for Byron to swim, so he howled and yelped until some of the men took pity on him and pulled the dutchman over for him to get upon. He did so and was hauled over to where his master was working. The appearance of the dog in mid-stream, with the light-load wheel discharge and the Nevada county pole line on the mountain side behind as a background formed so striking a picture that Engineer Theberath, with his camera ever handy, promptly perpetuated it.
Seven miles along the direct but impassible route of the pole line from Colgate, or twenty odd miles made up of, first, a trip across the river in the "flying dutchman," a climb up the canyon side, and lastly a drive consuming all the rest of the afternoon, lands one at the Nevada county power house on the South Yuba river. This is the third and last power house of the Bay Counties' system, although it was the first one to be installed. It seems as though it would have been -hard to secure a more difficult site on which, to erect a power house than that selected for the Nevada county plant, but the water power existed there, hence difficulties in installation had to give way to necessity. As it is, part of the foundations were cut out of the solid rock of the canyon side, while the outer portion of the power house is supported on piers, consisting of iron pipes carried down to bed rock in the river and filled with concrete. The lowering of the heavy machinery down the steep canyon side was an exceedingly difficult and at times hazardous performance, but nevertheless all was accomplished without accident, and so thoroughly was the work done that the plant has been in practically continuous operation since its completion, nearly six years ago. The diversion of a portion of the waters of the river into the flume is caused by a crib dam that has been thrown across the river some three miles above the power house, and the water thus taken is delivered to the water wheels under the pressure resulting from a head of 200 feet. In 1899, when the original plant was doubled in capacity, the water power was augmented by the building of a reservoir well up on the mountain behind the power house. This reservoir, known as Lake Vera, furnishes water to the power house at a head of 800 feet, to utilize which independent water wheels were installed in the power house. Lake Vera is supplied by mountain streams that are entirely separate from the South Yuba river and the lake presents an ample storage reservoir that can instantly be drawn upon in any emergency.
Two circuits carry power from the Nevada county power house to Nevada City and Grass Valley, then besides, the two circuits from the Colgate power house also run through to Grass Valley where the bulk of the power is consumed in the Nevada county division of the company. Aside from electric lighting, by far the greatest portion of electric power consumed in Nevada county is utilized in mining work, and its applications in this direction are most interesting. In the Reward Mine, for instance, a single electric motor having a capacity of 100 horsepower runs a stamp mill, a Cornish pump and hoist; and at the Brunswick mine are two 80-horsepower electric motors, one of which drives the air compressors while the other runs the 20-stamp mill, four concentrators and one rock breaker.
The most interesting mining installation in the vicinity of Grass Valley, from an engineering point of view, is to be found in the 350 horsepower electric motor which drives the air compressors of the Allison Ranch mine. Then there is the historical hoisting equipment of the Homeward Bound mine, which consumes 180 horsepower, and the Gold Hill mine equipment, which utilizes 350 horsepower in driving air compressors and the hoist. Other almost equally interesting applications of electrically transmitted power are to be found in the Bull