Pittsburg, McKeesport & Connellsville Trolley line uses Hemingray O Provo insulators

TROLLEY COMPANY'S POWER PLANT

TECHNICALLY DESCRIBED BY EXPERTS.

Expense Spared to Equip the Central Station Above

Gibson With Modern Generating Machinery.

The power plant of the Pittsburg, McKeesport & Connellsville Railway Company is 6,000 kilowatts capacity, built to operate an extensive current for lighting and power in the Connellsville coke districts of Western Pennsylvania. The output of the station is alternating current for both the railway and the general public supply, and it is trans­mitted at 22,000 volts to sub-stations for transformation to a lower pressure for local distribution, with rotary con­verters to supply direct current for the railways. A particularly interest­ing arrangement has been made in the equipment of the generating apparatus.

For the railway units, which are of 1,000 kilowatts capacity at 390 volts, compound Corliss steam engines are employed, connected to a central jet condensing system; while for the lighting units, which are also of 1,000 kilowatts capacity, but at 2,200 volts, compound Westinghouse steam tur­bines are used, each with an inde­pendent condenser. These are of the surface type, with circulating water supplied by centrifugal pumps driven by De Laval steam turbines. The live steam supply to the lighting unit tur­bines is passed through superheaters fired with natural gas, The plant was erected and equipped at a cost of about $1,000,000.

The plant is now the property of the West Penn Railway & Lighting Company, but was built by the Pittsburg, McKeesport & Connellsville Rail­way Company, a new consolidation. Up to the present time four important railway power stations have been shut down and at the completion of the lighting systems and outlying sub sta­tions three additional plants and eight lighting plants will have to be discon­tinued, power for the entire system be­ing supplied from the one central sta­tion. In the district through which lighting and power will be distributed are Greensburg, Manor, Jeannette, Penn, Irwin, Buena Vista, Uniontown, Connellsville and McKeesport. Six of the towns aggregate 65,000 inhabitants, ranging from 5,000 to 35,000, and there are 34 smaller towns of 500 to 2,000 population. It is estimated that fully 350,000 inhabitants may be counted on for patronage. The completed road will consist of 75 miles of through line and 50 miles of city and suburban line.

The power plant is located about 1 3/4 miles south of Connellsville, on the Youghiogheny river. There is thus a convenient supply of water at hand, and an excellent location for delivery of coal; and it occupies the electrical center of the system. The main part of the building is 207x82 feet inside, divided by a longitudinal brick wall, 18 inches thick, into a boiler room 35 feet 3 inches wide and an engine room 46 feet 10 inches wide. The total floor area is 165,000 square feet, or 15.4 square feet per rated horse-power. On the river side there are two exten­sions, each 18.5x30 feet in size, one containing the railway condensing equipment, and engineers' toilet and lavatory, and the ether the machine shop and tool room. The building is set some 65 feet from the river bank, and the high tension transforming apparatus is located in an isolated build­ing between the station proper and the river.

The building is of fire-proof con­struction. The foundations are con­crete, resting upon hard gravel. The walls are light brown brick, with ornamental pilasters between windows. At each end the walls terminate in para­pets, capped with sandstone flags and corbelled belt courses, cornices and blank windows to relieve the other­wise monotonous exterior. The roofs are supported by steel-arch trusses and are provided with Pancoast ventilators. In addition to the latter, further ventilation is provided by a row of small windows beneath the eaves. The interiors are lighted through large double sash windows. The floors and roots are of the con­crete and expanded metal construction, except the basement floor, which is of plain concrete. The clear height in the boiler room, from the floor to the lower chords of the roof trusses, is 39 feet, and in the engine room it is 41 feet; in this room there is a 30-ton three motor Cleveland plate-girder crane, the tracks for which are sup­ported on brick pilasters opposite those on the outside of the building.

Boiler Plant.

The boiler equipment comprises 12 Geary water-tube boilers, each of 400 horse-power capacity, 4,800 horse-power in all, set in six batteries of two boilers each. The fronts of the boil­ers are hung from a steel structure on the boiler room carrying the coal bins and the rear ends rest on special foot­ings, so that the boilers are supported independently of the brick settings. The fronts of the settings are finished with white enameled brick, which give the room an unusually fine ap­pearance. The elevated coal bunker in the boiler room extends the length of the room against the rear outside wall of the station and above the tops of the boiler settings. It is divided into two parts by one of the smoke passages, one part of 600 tons ca­pacity and the other, 300 tons. It is built of concrete and expanded metal on the steel framework mentioned, and its floor is level. Coal is obtained from local mines and is delivered over a spur track of the Baltimore & Ohio railroad at a cost of about 75 cents per ton. It is of the coking variety, used in coke ovens, and averages about 13,500 British thermal units per pound. A conveying system is to be installed to deliver it directly into the bins. In front or each boiler a spiral riveted chute, fitted with a Hunt coal valve, drops from the bunker, delivering coal to the firing space. It is intended to equip the boilers with mechanical stokers.

One of the Big Power Generating Corliss Engines.

The boilers are arranged for natural draft from two stacks of the Custodis radial brick construction, each 185 feet in height, and 10 feet in inside diam­eter. Each chimney is planned to serve eight boilers, as indicated in the plan, and the ducts from the boiler settings to the stacks are of riveted sheet steel. It will be noticed that an expansion joint has been inserted in each section. The main damper in the duct, next to each chimney, is op­erated by a Locke damper regulator. The space below one of the flues at the base of the stack is utilized us a lavatory and locker room for the fire­men, forming an extension to the boiler room.

The ashes are disposed of in an in­teresting manner. A concrete trough, covered by iron gratings, runs in front of the ash pits the full length of the building: it slopes 3 1/8 inches in 10 feet to a discharge opening at one end The ashes are carried out of the open­ing by flushing with water; and the ashes become available for filling low ground or may be hauled away, and the water finds its way to the river.

Railway Generating Equipment.

The generating machinery for the railway current occupies one end of the engine room and consists of three 1,550 horse-power Allis Corliss vertical cross-compound engines direct con­nected to 1,000-kilowatt Westinghouse alternators. The engines are 28 and 56X48 inches in cylinder dimensions and run at 91 revolutions per minute; the generators are 390-volt 25-cycle three-phase machines of the revolving field type. They are run in parallel and are synchronized by means of a motor actuated gear on the governor lay shaft, controlled from the switch­board An automatic speed limit de­vice has been installed, consisting of an auxiliary governor controlling a quick acting butterfly valve in the steam line to each engine. The re­ceivers between cylinders are provided with reheating coils, supplied with live steam from the throttle valve. The railway units have their own exciting machinery, which consists of two Westinghouse sets, each employing a 62.5-kilowatt 125-volt generator, direct connected to a 11 and 19x11 inch com­pound engine. Either unit is capable of furnishing the exciting current for the entire railway.

The railway generating units have also their own condensing plant. This comprises a 30-inch jet condenser, of the Worthington barometric type. It is provided with a vapor cooler and independent dry vacuum pump. It is designed to maintain a vacuum at 27 inches, with injection water at 70 de­grees Fahrenheit. The condenser pump is a duplex compound pump, 16x25x26x18 inches in size. The ex­haust pipes from the engines, each 24 inches m diameter, all lead to a cen­tral entrainer, which is piped to the condenser cone. Before entering the entrainer, each exhaust pipe is provided with a connection to the atmos­phere fitted with the usual relief valve. The tail piece from the condenser drops into a 6x9 foot elliptical hot well which is divided by a central brick partition to preserve the seal in the condenser discharge chamber should there be a loss of water from the second compartment. An interesting point in connection with the condens­ing plant is that any or all of the auxiliary machinery steam can be connected to it and operated condensing, a feature that has proved quite satis­factory in the case of the turbine-driver circulating pumps.

Lighting Equipment.

The lighting plant includes three, 1,000-kilowatt Westinghouse turbo-generator units, of the so-called com­pound or tandem cylinder type, which is now furnished by the builders in sizes of more than 400 kilowatts capacity.

Water Supply.

The water supply for all purposes except drinking water is obtained from the river, and as it contains no scale-forming impurities, is pumped di­rectly from the condenser hot wells to the boiler feed lines. There is also a general water supply furnished by a duplex steam pump in the basement which draws from the intake well and delivers to an elevated tank in the rear of the building between the two chimneys. The pump is operated automatically under the control of a pressure regulator. In the event of a brakedown [sic] breakdown of a condenser, a re­lief valve in the regular suction op­erates to transfer the suction to the general supply system. The feed pumps are in duplicate and are of the I2x7.5x10-inch Worthington duplex outside plunger type. Each suction is provided with a short standpipe at the pump serving as an air cushion to prevent water hammer, The pumps discharge into a 2,000-horse-power National closed heater and thence in­to a five-inch feed distributing main running parallel with the boiler fronts. The theater is supplied with steam from the exciter engine and other aux­iliaries, and has the usual steam bypass.

Power Transmission and Distribution.

For the railway systems, the alter­nating current is transmitted at 22,000 volts to substations, as already stated; but for the local sections of the rail­ways, a converter equipment is located in the engine room. There are three converters all told, of 250 kilowatts capacity each, operating directly on the three-phase 390-volt railway busses. All high-tension apparatus, however, is placed in the isolated building in order to confine fires resulting from high tension disturbances or the possible ignition of transformer oil. The ground floor of this building is used for transformers, those for the railway being ranged along one wall and those for the lighting along the other. The railway transmission system is served by duplicate banks of three 500-kilowatt oil insulated transformers, connected in delta and raising the voltage to 22,000 volts. Cables from the power-house enter from beneath the floor through 6-inch tile and the high-tension rise to the floor above through similar openings. In all cases of the passage through walls or floors liberal air insulation is depended on in place of glass or porcelain. High-tension switching apparatus is arranged on the third floor in independent systems. It is mounted on a 4x4-inch timber frame­work, which was filled with asphaltum after erection. The lighting system insulated water-cooled transformers, is to comprise five 750-kilowatt oil-spare, to transform the current from 2,200 volts, two phase, to 22,000 volts, three phase.

The high-tension circuits leave the building through 8 and 12-inch glazed tile, sloped to shed rain. Both light­ing and railway lines are carried on the same poles with transposition to minimize induction The cross-arms are 4x6-inch yellow pine, dipped in asphalt and wooden braces are employ­ed to increase insulation. The insulators are Hemingray No. 0 Provo type. They are provided with 8 and 4-inch petticoats and support the cable 6 inches above the lower rim and 12 inches above the cross-arms. A 13-inch standard locust pin with 2-inch shank is used without projecting sleeve. The poles are of chestnut, with 8-inch tops, spaced 100 feet apart, and are 35 to 60 feet in heighth, to compensate for the irregular profile of the right of way. The line wire is partly No. 1 solid copper and partly of stranded aluminum cable strung with screw couplings at the joints. The transpositions are executed with a simple 120-degree spiral between poles 25 feet apart, double arms being used tor safety. One line is carried straight through from station to station, and the other has two spirals. A river span, at the power-house is comprised of eight 1/2-inch silicon bronze cables strung with a center dip of one-thirtieth of the span. In addition to the transmission cables there are two 800,000 circular-mil stranded aluminum cables, one acting as a local railway feeder and the other as a metallic return. The lighting circuits are to be carried below the transmission lines. Incandescent lighting is furnished entirely on the 110-volt three-wire alternating-current system, with underground neutral. Constant potential arc lamps are also supplied from these hains. For street lighting constant-current series enclosed arcs are employed, with 7 1/2 ampere tub transformers located in the sub-stations. Power consumers are generally furnished with incandescent transformers.

The railway and lighting properties have been reconstructed largely as the result of the co-operative efforts on the part of the manager and engineer. The designs for the power station were executed by Messrs. Westinghouse, Church, Kerr & Company of New York, as consulting engineers for the Pittsburg, McKeesport & Connellsville Railway Company, as were the preliminary designs for the substations and overhead distribution system. The construction of the powerhouse was carried out under the direction of Mr. Thomas Elliott, general manager of the system and Messrs. R. W. Hunt & Company of Pittsburg, inspecting engineers of buildings and equipment. The electrical equipment for both the railway and lighting was furnished by the Westinghouse Electric & Manufacturing Company of Pittsburg. Mr. E. C. Converse, president of the Liberty National Bank of New York, is president of the West Penn Railway & Lighting company; Mr. J. S. Kuhn, president of the Pittsburg Bank for Savings, vice president; Mr. J. B. Van Wagoner, secretary and treasurer; and Mr. W. E. Moore, superintendent of construction. The headquarters of the company are at Connellsville, Pa.