Publication: American Electrician
New York, NY, United States
ELECTRIC TRANSMISSION AND DISTRIBUTION IN NEW ENGLAND
STATIONS OF THE CONNECTICUT RAILWAY
& LIGHTING COMPANY AT WATERBURY,
The distances over which water power is electrically transmitted in New England are, as a rule, moderate. When compared with the transmission lines of California they become quite insignificant so far as distances are concerned, and unlike these notable systems, the water power stations of New England have to deal with rather low heads of water.
The hydroelectric station of the New Milford Power Company at Bulls Bridge on the Housatonic River in the town of Kent, Conn., has the distinction of being the largest electric generating station using water power in New England. It possesses the largest head of water, the highest transmission voltage and the longest transmission line of any of the many hydroelectric stations in New England, while in point of capacity it exceeds any of the famous water power stations of California, save that at Electra and Colgate.
Bulls Bridge is the site of a highway crossing over the Housatonic River, and is in that part of the valley where the river has a continuous rapid descent with steep, rocky hills close on either side. Near the bridge the valley narrows and the river has cut its way down into solid rock. Below the bridge the river makes a turn of nearly 90°, and then, after flowing nearly straight for about a mile, takes another turn that brings its general direction back to within a small angle of its former course. At a short distance above the bridge, a dam has been built across the river, and a canal starting from one end of the dam skirts the hillside for a distance of about two miles and then terminates in a forebay, where the water stands no feet above the surface of the river below the second bend just mentioned. From this forebay a steel pipe carries the water down the steep hillside to the power-house on the river bank. This type of water-power development, comprising a rather long canal, a moderate volume of water and a gradual fall in a river concentrated at a single point, so as to give a head of one to several hundred feet, is quite common in California, but has seldom been attempted in New England.
The steel pipe leading from the fore-bay is 13 feet in diameter, and another pipe 8 feet in diameter will subsequently be erected. This 13-ft: pipe after reaching the power-house runs along outside of its river front, and connects with seven smaller pipes that pass through the wall to the water-wheels inside. At the end of this horizontal section of the main pipe, which shrinks in diameter as pipes from the wheels are taken off, it turns into a vertical position and extends to an elevation equal to that of the crest of the main dam. The stand pipe thus formed acts to relieve any undue pressure such as might be caused by the hydraulic ram action following the shutting down of some water-wheels too quickly.
The power house is built entirely of concrete and steel, the foundation being carried to solid rock. The station is formed into one main building 115 feet long by 48 feet wide with an annex in the rear and at the center 44 feet by 48 feet. In the main building are placed the wheel cases, hydraulic valves, governors, generators and exciters; while in the annex forming a part of the main building are found the switch-board, oil switches and electrical connections. In the rear of the annex and separated by a concrete partition wall a space 18 feet by 48 feet is devoted to transformers and lightning arresters.
The water wheels used are of the most recent high-speed type made by the Platt Iron Works Company, of Dayton, Ohio. They are 31 inches in diameter and are placed tandem, being direct-connected to the generators and governed by Lombard water-wheel governors. Each pair of wheels has a capacity of 1750 horse-power, making a total for the six units installed of 10,500 horse-power. The three-phase generators have a capacity of 1000 kilowatts each and furnish current at 60 cycles and 1150 volts. They possess a momentary overload capacity of 50 per cent and a guaranteed overload capacity for several hours of 25 per cent. The voltage is stepped up in six oil-cooled transformers in banks of three to 33,500 volts for transmission.
The energy from this water power plant is used on the extensive system of the Connecticut Railway & Lighting Company in Waterbury, New Britain and Cheshire. Two sub-stations are located in Waterbury from which electricity is supplied to all of the street railway lines, as well as to power and lighting circuits. The sub-station in New Britain is somewhat similar to the large sub-station in Waterbury in equipment and feeds street railway, light and power circuits. The sub-station at Cheshire is devoted exclusively to street railway work.
Two three-phase transmission lines from Bulls Bridge run to sub-station No. 1 of the Connecticut Railway & Lighting Company at Waterbury, Conn. The Station is located on the west bank of the Naugatuck River on the outskirts of the town. Each of these three-phase circuits is made up of three bare aluminum wires having a conductivity equivalent to No. 00 copper. Energy delivered to the line at Bulls Bridge at about 33,500 volts reaches sub-station No. 1 at Waterbury over 30 miles distant with a loss ranging from 4 per cent to 7 per cent, depending on atmospheric conditions, being greatest of course during wet weather. Transformers at this station reduce the voltage to 2300 for overhead transmission through Waterbury to sub-station No. 2, situated in the center of the town. Current at a p