Publication: The Journal of Electricity, Power and Gas
San Francisco, CA, United States
A ONE HUNDRED AND TEN-MILE TRANSMISSION.
THE Washington Water Power Company, Spokane, is about to begin the commercial operation of its 110 mile transmission line, which is the longest in the Northwest. In the generating station two 2250-kilowatt, 4000-volt, revolving field generators, each direct connected to a Victor turbine, operating under a head of seventy feet, have been installed. The electric machinery, including generators, transformers, switches, lightning arresters, etc., was built by the General Electric Company. The switchboards are installed on a gallery overlooking the whole power house, and all main busbars are in separate pottery compartments underneath the gallery. Two sets of bars allow the city service and the transmission system to be separated when necessary. All the generator switches are of the General Electric Company's form H, motor operated, remote control type. These switches operate so promptly upon closing the relay switch on the switchboard that no difficulty is encountered in synchronizing machines. The exciter is direct connected to a separate water-wheel without governor. A Lombard governor is installed to operate each of the larger generators; only one of these governors, however, will be used at a time, as a practically constant gate opening on one wheel will be used, allowing the governor on another wheel to regulate for the whole station.
Three water-cooled transformers (with one spare for emergencies) step the voltage up from 4000 to either 45,000 or 60,000 volts, depending upon connection, for the long distance transmission. There are no high tension switches, other than disconnecting switches, installed between the line and the transformer primaries. Lightning arresters are installed, each single pole arrester being in a separate brick compartment extending from the lower floor of the building to the high tension wires, which are near the roof.
The line is approximately 110 miles long to the furthest power user. A portion of it runs through marshy or boggy country where, considerable trouble was experienced last winter from ice forming around the pole butt and finally lifting the pole out of the hole. This difficulty was overcome by putting horizontal cross pieces on the butts underground. The line consists of three No. 2 solid copper wires, with 60,000-volt Locke insulators and iron pins. These pins are made of about three-inch wrought iron with cast iron shanks, for insertion in cross-arm and lead threads. There are six substations, each equipped with three-phase, step-down, water cooled transformers, varying in size from 100 kilowatts to 750 kilowatts, with primary taps for 60,000 or 40,000 volts, according to line pressure. Each substation is equipped with an automatic high tension oil switch mounted in a separate brick compartment above the panel and connected between the transformer primary and line.
The power will be used almost exclusively for mining purposes, the most notable installation being at the Standard and Hecla mines, where four General Electric, 300 horsepower induction motors will be used to drive compressors, hoists, etc. One of these motors will be geared direct to a hoist. There is an aggregate of about 800 horsepower in synchronous motors and the balance in induction motors. The synchronous motors will be started direct from the line through low voltage taps on the transformers. The plant has already been operated for some time at 60,000 volts, but with no load at the end of the line, and no defects have been encountered.
|Keywords:||Locke Insulator Manufacturing Company|
|Date completed:||August 23, 2013 by: Bob Stahr;|