AC verses DC current
The motors in LARy's streetcars were designed to operate on electricity furnished at a pressure of from 500 to 600 volts direct current (DC); this was standard practice in the industry at that time. Direct current has the defect, however, of substantial line losses in proportion to the distance transmitted. As early as the 1890s it had been recognized that the best practice in larger electric-railway systems was to generate electricity at high voltage at a power house or central station and transmit it as alternating current (AC) to "substations" located around the system. Transformers would then reduce the voltage and motor-generator sets would convert the alternating current to direct current. Heavy "feeder cables" carried the current to numerous points along the line from the substations to points where they were tapped into the trolley wire above the track. Superior to the motor-generator set was the synchronous, or rotary converter, developed by the First World War, and the mercury-arc rectifier developed by the late twenties. On the LARy, a mixture of older and newer equipment would serve until the end, as the newer machines were not so superior as to justify replacing the older before their useful life was over.
Los Angeles Railway Powerhouse
The LARy's powerhouse was located at the corner of Central and Wilde Streets, near its original car house and shops. In 1903, the powerhouse contained a 78 by 107 foot boiler room with ten 250 horsepower oil-burning steam boilers. The steam was then fed into the engine and dynamo room, 94 by 137 feet, where five reciprocating steam engines of various makes drove seven generators having a total output of 2,840 kilowatts. While this output had long been in the form of low-voltage direct current to be fed directly into the trolley wire at various points, LARy was now beginning to produce high-voltage alternating current for distribution to substations. An industry periodical reported that LARy had "built two substations, and have in course of construction a third station. The first station is located in the southwestern limits, at what is called Agricultural Park. This station consists of a building in which is installed one 600-kilowatt and one 400-kilowatt motor-generator set. Their second station is located in the western limits, and there is installed in this station one 400-kilowatt motor-generator set, with foundations for two more machines of the same capacity. The third station is located just north of the central portion of the city, in which provision has been made for three motor-generator sets of from 400 to 600 kilowatts capacity. These substations are all of the same general design." An additional 400-kilowatt motor-generator set had been installed in the engine room of the powerhouse. The second substation referred to was the Knob Hill, or Westlake Substation, and the third is the Plaza Substation. Of these first three substation buildings only the Plaza Substation remains.
Not only did efficiency of power distribution for the existing system dictate development of a substation network, but the continuing expansion of LARy's outer limits did so as well. On March 31, 1903, LARy expanded its operations as far as the Garvanza District, running its cars over the Pacific Electric’s Pasadena Avenue (North Figueroa Street) line as far as Avenue 61. This was replaced by service over its own new line as far as Avenue 60 and Monte Vista on May 1, 1904. A substation north of the central business district was called for. There was increasing traffic on existing lines in the Eastlake (Lincoln Heights) district, and with the construction of the Garvanza line the Plaza Substation was the initial answer to this need.
Construction of the Plaza Substation
While LARy may have decided to build a substation north of downtown at an earlier date, the precise Plaza site cannot have been assured until after a public land auction was completed, the results confirmed by the court in April and May of 1903. The property was then put in the name of the Huntington-controlled Land Company. This occurred at the same time that Huntington was being forced to accept Harriman’s Southern Pacific as a partner. On September 12, 1903, it was reported that the Los Angeles Railway had taken out a building permit from the City of Los Angeles for a two-story brick building at 610-616 Olvera Street and 609-615 Los Angeles Street. The building’s estimated cost would be $6,000 (presumably this included only the building and no electrical equipment.) LARy would act as its own contractor: E.T. Cobb was recorded as architect.
Two drawings for construction of the Plaza Substation bear the name of E.S. Cobb, Engineer. One is dated June 26, 1903 and shows three elevations and two sections of the building. Another is a plan showing a preliminary design for the structural framing for the "Substation at Plaza" no date. It is therefore established that the building permit reference to "E.T. Cobb" was in error referring to E.S. Cobb.
(At the same time, LARy obtained another permit; this was for a one-story, 264-by 323-foot brick building on South San Pedro Street between 53rd and 54th, estimated cost $15,000. Although identified as "sub station" in the newspaper report, the dimensions of the building make clear that this was what was later known as the Division Two Car House. A 1904 map shows a "South Park Sub-Sta." at that general location as well as a car house and shops. This substation, if it existed, must have closed when the Slauson Substation went into service in about 1907, six blocks away at Slauson and Towne.)
A photograph showing the building nearly completed, except for the roof covering and clerestory windows, dated "12-11-03" confirms the 1903 date for the Plaza Substation. On the annual assessment date, the first Monday in March, 1904, the County Assessor assigned a value of $8,900 to the improvements on LARy’s Olvera Street parcel, which remained unchanged over the next three years, indicating that the building and its fixtures were complete as of the 1904 assessment. The building was reported as: 61'-6" x 107'-0" x 44’-0" to eaves. Brick Bldg. with composition roof, wood sheathing, combination wood & iron trusses, concrete floor & foundations. Walls are 21" for 4’ above top of basement, there [sic] 17" for 12’ and the rest to eaves 13".
The original motor-generator set or sets of 1904 were replaced in 1907 with a 600-kw Westinghouse motor-generator set weighing 77,950 lbs. and three 1,000-kw Westinghouse motor-generator sets weighing 142,910 lbs. each. A 1913 inventory and valuation also listed eleven Westinghouse 475-kw 50-cycle 15,000-to-2,300-volt transformers and two 2-kw 15,000-to-110-volt transformers, a direct-current switch board with meters, circuit breakers, switches and miscellaneous material; 15,000-volt oil switches in place, a water cooling system, a compressed air system, miscellaneous tools, a direct-current motor, 50 horsepower, 500 volts, 550 RPM and blower; two 15 kilovolt incoming circuits from entrance to loop bus; a 15-kv loop bus; four 15-kv circuits from the loop bus to the transformer bank; four 2.2-kv circuits from the transformer bank to the m-g sets; four sets of structural work, insulators, etc., on the d.c. ends of the machines; d.c. wiring for each of the four machines; feeder cables and connections, bus copper, miscellaneous wiring, etc.; and entrance tiles and fixtures. This valuation placed the reproduction value of the Plaza substation's equipment at $120,662.43; present value after depreciation, $96,454.13; reproduction value of the building was $21,163.60; present value, $16,930.88 (neither of the latter including the 2˝% for contingencies.) The power conversion machinery and the switchboards containing the instrumentation and controls were located on the main floor, just above the level of Olvera Street; due to the slope of the terrain to the east, the basement opened on Los Angeles Street.
The Plaza and the other substations were connected by "feeders" to the trolley wire at numerous points. A LARy drawing titled "Feeder Index," drawn "12-4-31" and revised for the eighth time on "12-1-55" shows fifty feeders numbered 1 through 77, with twenty-seven of the feeders blanked out, representing former feeders to abandoned lines. Some feeders were noted as connecting with others through "sectionalizing switches."
The chart shows which substation fed which feeders. For example, as of that date, Plaza fed No. 1, Spring Street (sectionalizing with No. 28, Main Street No. 2, fed by Central), No. 2, Broadway (sectionalizinq with Nos. 73, East Twelfth Street,, fed by Central, and 77, Pico Blvd. No. 1, fed by Sentous), No. 4, North Broadway No. 1 (also fed by Huron), No. 13, East First Street (also fed by Soto, and sectionalizinq with No. 43, East Fourth Street No. 1 (see below)), No. 20, Main Street No. 1 (also fed by Central), No. 42, Brooklyn Ave. (also fed by Soto, and sectionalizing with No. 6, Boyle Heights, fed by Soto, and No. 43, East Fourth Street No. 1 (also fed by Soto and Division One, and sectionalizing with No. 13 (see above)).
A typical feeder is No. 13, East First Street, which served the 'P'-line, West Pico and East First Street, traditionally LARy's heaviest line. The LARy drawing, dated "Nov. 1923," with revisions up through "1-3-52," shows that the feeder, after emerging from the Plaza Substation, followed the east side of Alameda Street. It went as far as First, then east along the south side of First to Vignes Street, then on the north side of First to Boyle Avenue. Thence on the south side to Breed Street and on the north side to Soto Street, then along the west side of Soto to the Soto Substation. Taps into the trolley wire were located at nineteen points along First between Alameda and Soto. A sectionalizing switch to Feeder was located at First and Alameda. Insulators in the trolley wire isolated the section fed by No. 13 from other sections; east of Soto, First was fed by No. 6, Boyle Heights; crossing Main Street, First was fed by No. 20, Main Street No. 1, and west of Main, by No. 1, Spring Street.
-David Cameron, 1990