Publication: Electrical World
New York, NY, United States
CANADA is a region of gigantic water powers, which have waited for the advent of electricity to he utilized for the many purposes to which they are applicable. Perhaps the fittest installation for the development and transmission of the power of falling water extant is that of the Chambly Manufacturing Company. at Richelieu Village, Quebec.
At this point, about 25 miles distant from Montreal, the Richelieu River falls through a long series of rapids. From early days a wooden dam between Richelieu Village on the one side of the river, and Chambly on the other, has been in existence, supplying power to a few small mills. The new structure which takes its place is one of the finest examples of hydraulic engineering on the continent, consisting of a massive concrete dam, in which, as an integral part, is built the power house, with a capacity of 20,000 horse-power.
This dam, which is shown in the initial illustration, is about anon feet long, 6 feet wide at the crest, and constructed of a concrete composed of the broken rock of the river bed, mortared with sand from the vicinity and American cement. The back is vertical throughout, and the apron is curved so that the overflow water is discharged horizontally, obviating any destructive washing action at the base. A liberal use of one-half inch iron rods, incorporated with the mass of the concrete, gives great strength to the structure, and a surface dressing of neat cement insures the greatest impermeability. This is said to be not only the most carefully constructed but also the largest concrete dam on the continent.
The dam consists of three portions, two of which run perpendicularly across the course of the river, while the third and middle part is parallel with it. In the lower third of the dam, and near the right batik of the river, is built the power house. Here the dam consists of two levels, or steps, over which is built a structure of steel beams and brick walls, 308 by 51 feet, for the protection of the machinery. The upper level, which is about 2 feet above the surface of the water in the lake formed by the dam, will contain the switchboards and controlling devices and such offices as are necessary. In this part of the dam eight rooms, or flumes, each about 20 feet square and to feet high, are constructed, their arched openings being under the water level, for the reception of the wheels. These, of the horizontal-shaft pattern, number four in each flume, each wheel being 46 inches in diameter. These wheels are mounted tandem on one shaft in two pairs, between the wheels of each pair being a large cast-iron box communicating with the draft tubes, which extend through the solid concrete of the lower step of the dam to a point below the level of the tail water. The draft tubes are built of sheet steel, and are 9 1/2 feet in diameter where they leave the boxes, and 10 feet at their outlet. The upper extremities of these being one behind the other in the line of the shaft, necessitated their construction in a curious skew curve. This installation seems to run to superlatives, since these draft tubes are the largest ever constructed. Their bedding in concrete excludes all possibility of leakage, and it is confidently expected that the full advantages of the head of 28 feet will be realized by their use, although the wheels are but a few feet below the level of the intake water. Under this head. and at the speed of 153 r. p. m., each wheel will develop660 horse-power, or a total of 2640 horse-power to each shaft and flume.
The governing of the wheels will he by means of Giessler electromechanical governors, similar to those in use at the Lachine plant. These are relay governors, the revolving balls actuating a small lever which closes electrical contact at speeds higher or lower than that for which the instrument is set. These contacts control electromagnets which operate clutches on the main shaft geared to the gate of each gang of wheels. It has proven an excellent and reliable governor in other large hydraulic installations, notably in that at Lachine Rapids, described in THE ELECTRICAL WORLD of October 2.
At present only four of the eight sets of wheels are being installed, together with two 28-inch wheels, giving 750 horse-power for driving the exciters of the large dynamos. The whole of the hydraulic machinery was furnished by the Stilwell-Bierce and Smith-Vaile Company, of Dayton, Ohio, and reflects much credit upon that concern by the solidity of its construction and the great accuracy with which the parts of the heavy wheels and draft tubes were assembled at Chambly by its constructing engineer, Mr. H. A. Wright.
The shaft of each gang of turbines passes out horizontally through a circular steel bearing plate on the down-stream vertical face of the upper step of the dam, and is directly connected to a 2000-kw generator, giving two-phase current at 60 cycles per second and 12,000 volts.
These machines are of the inductor type, having no moving wire. The inductor is about to feet in diameter, and of very massive construction. The single-circular field coil is wound on a brass spool of about to inches face by an equal depth, and completely surrounding the inductor. The armature is in two parts. The insulation of these armatures is necessarily most massive and substantial. All the dynamo machinery is now under construction by the Royal Electric Company, at Montreal, front designs by the Stanley Electric Manufacturing Company, of Pittsfield, Mass.
In the space above the flumes in the upper portion of the power-house dam, a large conduit has been made for the reception of the leads from the dynamos to the switchboard Lead-covered, tubber-insulated cable will be used for these. In the walls of the power house a number of large terra-cotta pipes, about 3 feet long, bent to a quarter circle, with the convexity upwards, have been built in, and through these the cables leading to the pole line will pass out without touching anything between the insulators inside and outside the building.
Two pole lines will be constructed to Montreal, either one being sufficient to carry the load. This construction was adopted to minimize the chances of accidental breakdown, and to make repairs easily possible without danger to workmen. The poles are of chestnut, none being less than 40 feet long. Each pole carries two cross arms, the us