Publication: American Electrician
New York, NY, United States
notice the exhibit shown in Fig. 18. This shows a pole-top that had been burned away and the insulator and pin. When the pole was found it had been burned as shown, but the insulator and pin were still in position, being held there evidently by the winding of galvanized wire, while the zinc wrapping had protected the pin and thus kept the insulator from falling. The lesson to be drawn from this exhibit is obvious. The entire line to Stockton consists of No. 1 B. & S. gauge seven-strand bare aluminum wire, weight 401 pounds to the mile. Soft aluminum wire is used for the wires and the poles are set 180 ft. apart. For the Folsom line No. 4 medium hard-drawn copper wire has been used with No. 6 annealed copper tie wires. On account of the greater weight of the wire the poles on this line are set 135 ft. apart. The company installed both aluminum and copper lines so that it could observe the working results of both under similar conditions and determine which was the best material to use for future extensions. Thus far the wires have not been in operation long enough to give conclusive results.
Fig. 14-E is a view of the company's Folsom sub-station and shows how the 11,000-volt and 2200-volt secondary wires are carried up and over a steam railroad track and two pole lines of another transmission company. The poles are of sufficient height and close enough together so that a broken wire will not come in contact with a train, and further protection is provided by a wire net between the poles and above the track.
At the Stockton terminus of the 80-mile, high tension transmission is the neat brick sub-station shown in Fig. 15. This view also illustrates the high-tension switching apparatus and lightning arresters, which are of the same types as those shown at the power house. The sub-station is equipped with step-down transformers and as a rule does not require an attendant. There are installed in the station three 150-kw. and three 300-kw., oil-insulated, water-cooled transformers. These transformers are constructed, with taps for 30,000 to 60,000 volts on the primary and 2200 volts on the secondary, with an allowable variation of 5 per cent above or below. The switchboard, Fig. 20, has three panelsone for the transformer and two for the secondary feeders, equipped with oil switches, lightning arresters, instruments, etc.
In Stockton the company supplies a commercial service of about 6000 incandescent lights and about 300-horse-power in motors. It has only been operating since early in 1904, and is competing with an old-established company. In the business district of the city the company is placing its commercial three-wire, 220-volt secondaries underground in Edison tubing.
A feature of the sub-station, as well as of the power-house, is the precaution taken in installing the telephone instruments. In Fig. 19 is shown the apparatus in the. Stockton station. The telephone is mounted on the upright portion of a platform which is insulated from the concrete floor by glass insulators. A person talking has to stand on this platform in order to reach the instrument. The two line wires terminate above the telephone, as shown, in special fuses mounted on slate panels that are in turn insulated from the wall. A knife switch with a long break is placed above each fuse so that the line .can be cut out when the fuse is replaced. The telephone line from the power house passes through this sub-station and then to the company's office in the city and the wiring is arranged so that the talking circuit may be cut out when no one is at the station. Knife switches are provided for cutting the talking circuit in and for cutting out either the power house or the office end of the 1ine. No trouble is had in talking over the 80-mile circuit to the power house or over the entire Ho miles to Folsom. In the power house a special concrete booth has been built for the telephone and the latter is also insulated in the same manner as at the Stockton sub-station.
At various points along the Stockton transmission line the company has been able to develop a good business in the supplying of power. This line runs through some of the richest mining camps in the Mother Lode and the outlook for further development is very good. An electric railway is to be built from Ione to Jackson and Sutter Creek and the American River Electric Company has the contract for supplying the necessary power.
A spur of the line runs to the Jenny Lind mining section, where the sub-station shown in Fig. 16 has been erected to take care of the business. The equipment consists of three 100-kw. transformers which reduce the voltage to 2200 or 4400 volts, the latter being used. The power supplied from this station is utilized for the operation of gold dredging plants. At Nashville a similar sub-station has been installed, the power in that case being used for quartz mining.
The Folsom sub-station, at which the 30-mile, high-tension line terminates, is constructed of corrugated iron and covered with P. & B. roofing. The interior of the sub-station is shown in Fig. 21. The equipment consists of four (one spare) 300-kw. transformers stepping-down from 30,000 to 2,200 or 4,400 volts and three 100-kw. transformers stepping-down to 11,000 volts. The entire output of this station is sold to the Folsom Development Company, a corporation which has entered extensively and systematically into the gold dredging business in that vicinity. This company has purchased 18,000 acres of land in that section; has two dredges in operation near Folsom; is operating two or three at a point four miles below, and is planning to build ten or a dozen more in the near future. As this phase of electric power development is an interesting one, some mention will be paid to it.
In Figs. 22 and 23 are shown two of the Folsom Development Company's dredgers at work. These dredgers are built on the spot, a pit being excavated for the purpose, and if the land is not near enough to the river to give water to float the boat, water is pumped into the pit. The gold-bearing soil is a gravel deposit that has been washed down in old river channels from the rich Mother Lode district farther up on the mountains. It has only been since electric power could be obtained at a cheap rate that it has been profitable to work this ground, but judging