Publication: Electrical World
New York, NY, United States
The Electrical Power Transmission Plant at Three Rivers, Quebec.
BY H. R. LEYDEN.
The first long-distance electrical-power transmission plant to be installed in Canada has now been in operation for six months with most satisfactory results, both from the engineering and financial standpoints. This plant was installed by the North Shore Power Company to transmit power from the waterfall at Grande Chute on the Batiscan River over a distance of 17 miles, to the city of Three Rivers. The present development delivers boo horse-power at the end of the transmission line, but the plant has been laid out with the view of largely increasing this for future demands. The most interesting feature in connection with this transmission plant is the novel method in which the two-phase power is applied to an old electric-light plant, which formerly operated single-phase alternating apparatus and a series-arc system by steam power. The new power is applied to the old system with surprisingly few changes in the distribution.
The old plant consisted of two single-phase alternators of 1500 and 750 incandescent lamps capacity, and of two series-arc dynamos, one of thirty-five and the other of fifty lamps capacity. All the dynamos were belted directly to high-speed steam engines. There was also a suitable boiler plant using bituminous coal for fuel. In connection with the electric-lighting plant there was a pumping plant capable of delivering 1,000,000 gallons every twenty-four hours to supply water to the city. Both the lighting and the pumping plants were owned by the municipality of Three Rivers, which had operated them for over six years. A careful system of accounting has shown, however, that, even with higher rates for service than are charged elsewhere by private companies, this municipal plant was running behind every year. The city authorities, therefore, decided to dispose of the plant, and stop the continued outlay caused by the yearly deficits in their lighting and pumping account. The plant was accordingly sold to the North Shore Power Company at a large reduction from its original cost and a contract was made with the company for supplying the street lighting and pumping service required by the city at rates customary in cities of this size and character.
The company, in order to reduce the cost of such service, decided to employ water power, which is quite plentiful in this portion of the Province of Quebec. The most available powers were at considerable distance from the city, and the cost of transmission was at first thought to be too great, but a careful investigation showed that, in utilizing the Grande Chute of the Batiscan River, the cost of the transmission line would be comparatively small, and that the necessary investment for the hydraulic and electrical plant would pay a very good return.
This beautiful waterfall was almost ideal for a development of this character, as the waters of the Batiscan at this point tumble over rocky ledges, giving a total fall of 60 feet within a distance of too yards. The Batiscan River has a large and regular flow of water at all seasons of the year, being fed by large lakes a long distance back in the Laurentian Mountains. The power of the whole fall is estimated at over 3000 horse-power, but only a portion of this is utilized by the present plant. In addition to this large and constant flow of water, this fall has the particular advantage of being free from a bugbear of all water-power plants in told climates—frasile. This is a peculiar ice formation differing from both anchor ice and slush ice, and more dangerous to water wheels and racks than either, as it often sinks below the surface of the water, especially if the current is swift. It forms only in open water, and rises to the top if there is little motion, so that the only reliable method of avoiding its dangers is to have a large body of still water above the dam. Immediately above the Grande Chute the water is quiet and covered with ice in winter for 1 1/2 miles up stream, so that there is no fear from this source.
This magnificent power seems to have been designed by nature for the purpose to which it is now being put. Nearly all the dam work for its utilization had already been done by some volcanic upheaval, so that it only required the expenditure of a little over $1,000 on masonry work to render the large, natural force of this power available in a very convenient form.
It may be seen from the illustrations that only a short length of masonry was necessary to form the dam and head-gate construction. The stone for this work was procured on the spot by blasting away portions of the ledge, and the dam was built directly on the granite rock which formed the crest of the fall. The artificial dam only extends half way across the stream, the other part being a natural spillway.
From the head gates the water is conducted in a steel flume down through a natural trench directly underneath the power house, a distance of 400 feet. The flume is 6 feet 6 inches in diameter, and is built up in 6-foot lengths of one-quarter inch boilerplate,supported by piers every s feet. It is the intention to cover the flume before cold weather sets in with spruce boughs, over which the snow will make a protective blanket against the intense cold of winter.
The power house is a substantial stone structure built on a flat ledge of granite. It is 62 feet in length by 36 feet in width, and is designed in such a way as to allow an increase of the present equipment as the demand for power grows beyond the present installation of 800 horse-power.
The lower end of the steel flume terminates in a large head sheet, which is provided with a gate valve for drainage when the water is shut off. A few feet from the lower end, and directly beneath the wheel cases, the water for the turbines is taken from the feeder or flume by two branch pipes which lead vertically upward, and connect through shut-off gates with the wheel cases.
The wheel cases are placed on the power-house floor, supported by iron girders set in heavy stone walls. They are built of 5-16-inch boiler plate 6 feet in diameter, with heavy cast iron