[Trade Journal]
Publication: Arnold Bulletin
Chicago, IL, United States
no. 13, p. 3-14, col. 1-2
THE HYDRO-ELECTRIC PLANT
OF THE SPRING RIVER POWER CO.
THE Joplin mining district, or the lead and zinc fields of the state of Missouri, extends from Galena, Cherokee county, Kansas, east through Jasper county, Mo., to Carthage, and from South Joplin, Mo., north as far as Alba and Neck City, comprising in area about 150 sq. miles. The mining industry in this section dates back to about 1878, during which time it has been continually increasing in volume, until the present output of zinc and lead ores amounts to slightly over $7,000,000 per year, this consisting of nearly 200,000 tons of zinc ore and perhaps 25,000 tons of lead ore.
At first lead only was mined, the ore being found very close to the surface of the ground. Later when the surface ore was exhausted and it was necessary to go deeper for the lead, quantities of zinc ore were found. Since that time the importance of the zinc industry has rapidly increased until now it is far in excess of the lead industry.
Zinc ore is found in pockets, and the amount of ore upon any particular mining claim cannot be accurately determined by prospecting. This makes the life of any particular shaft very uncertain, but three years may be taken as the average. Some pockets are worked out within a few months, while others are worked for a period of five or six years before being exhausted.
This characteristic of the zinc fields makes it necessary to change the location of the mills at frequent intervals, and as a result of this, the machinery is installed at the least possible expense and all installations are of a very temporary nature. One direct result is a very low efficiency in operation. Steam plants in comparatively small units and very cheaply installed do not give a very high mechanical efficiency and result in a high cost of power to the mine operators. This position was recognized by the capitalists interested in certain Joplin mines, and as the result of their observations it was decided that the water power along Spring river should be investigated with a view to utilizing this power throughout the mining district. For this purpose the Spring River Power Company of Joplin, Mo., was organized. This company is composed of Chicago men. Mr. Francis W. Farwell is President, Mr. Jamot Brown Vice President, and Mr. Samuel Brown, Jr., Secretary and Treasurer. The Arnold Company of Chicago was commissioned to prepare complete plans and specifications for the proposed development and later they were awarded the contract for the entire construction.
THE HYDRO-ELECTRIC PLANT.
The improvement consists of a hydro-electric plant located near Lowell, Kas., at the confluence of Spring river and Shoal creek. At this point a dam has been constructed and turbines and generators have been installed, as well as step-up transformers and the necessary switching apparatus. From this point a transmission line leads through the zinc district by the cities of Galena, Joplin and Webb City, in all about 30 miles. Four sub-stations have been constructed, and from them secondary lines lead out to the mills that are supplied with electric power. For the transmission line a voltage of 33,000 was chosen, and for the secondary distribution a voltage of 2,300. In taking up the description of the property somewhat in detail, it may be well to begin with the work at Lowell and take up the various parts of the property in sequence.
DAM.
The dam is constructed entirely of concrete resting upon rock in and below the river bed. It consists of the dam proper, nearly 500 ft. long and an earth embankment with a concrete core wall about 800 ft. long. The dam, as seen in the cut, Fig. 6, consists of two turbine rooms, each 99 ft. long, between which is located the generator room, 45 ft. long by 30 ft. wide. At the north end of the turbine room the controlling parts are located, occupying a distance of 95 ft. in the length of the dam. At this point are installed 5 Taintor gates, and directly below the gates on the down-stream side of the dam, are the aprons affording a spillway for the water allowed to go through the gates. From the north end of the dam a core wall and an earth embankment extend northwesterly for a distance of about 800 ft. At this point the embankment runs into the road leading from Lowell to Varck. The grade of this road has been raised for a distance of about three-quarters of a mile beyond the end of the core wall. At a point along this road about half a mile from the dam sluice gates are installed, which makes it possible to divert a part of the river's flow during flood time. The water so diverted flows into Spring river about three-quarters of a mile below. The topography of this section which makes this natural overflow channel available adds very much to the desirability of the chosen location for a power plant.
POWER PLANT LAYOUT.
The layout of the dam and power house is somewhat unique. As shown in the cut, the generator and turbine rooms are part of the dam. The normal elevation of the water in the tail-race will be about 113 ft. The floor of the turbine room is at an elevation of 121 ft. and from this floor the draft tubes under the turbines, project downward into discharge tunnels built in solid concrete in the lower part of the dam. The normal elevation of the headwater originally was to be 137 ft., but later the plans were so changed as to allow this elevation to be changed to 141 ft., thus giving an available head of 28 ft. The turbines are installed on the floor of the turbine room and are practically situated on the river bed just above the dam. This method of entirely doing away with the head-race is very advantageous, as there is no question of difficulty arising from any currents which often are found in the head-race of ordinary construction.
In each turbine room are installed four pairs of horizontal turbines, all mounted on one shaft. The shaft extends through bulkheads into the generator room, where it is directly connected to the generator. This exceedingly simple construction is the most desirable, as in the operation of the plant there is absolutely nothing necessary but to attend to the bearings.
In front of the turbine room is installed a grid-bar rack supported by steel columns spaced 5 ft. Provision is made for mounting sliding gates between these columns in case it is desirable to shut the head-water off from the turbine room in order to make repairs on wheels.
The roof of the turbine room consists of heavy planking laid over the steel beams connecting the top of the columns with the dam proper, which forms the back of the turbine room. This construction is clearly seen in Section E F of Fig. 6. Section CD is taken through the generator room and shows the relative location of the generators, exciters and switchboard. Section A B shows the construction of the Taintor gates. The axes of these gates consist of two 15-in. 42-lb. I beams securely riveted together with steel plates and with necessary angle plates for attaching the wooden framing. The radius of these gates is about 132 ft. As plainly indicated in the cut, they are designed to allow the water to pass through underneath the gate. By means of the controlling gates, the head-water can be kept at any desired height. The gates are designed to take care of the excess water at all ordinary times. In case of extreme high water, the overflow is to be taken care of by the special cut-off referred to in a preceding paragraph.
TURBINES.
The turbines were furnished by Jas. Leffel & Company of Springfield, Ohio. There are two units, each consisting of four pairs of their latest improved 422-in. center-discharge, horizontal turbines connected together tandem on horizontal shafts. The turbines are designed to run at from 180 to 200 rev. per min. and will develop 80% of the theoretical efficiency under a 24-ft. working head. Each pair of turbines is mounted on heavy base plates, which in turn are mounted on heavy steel beams, forming the turbine room floor. Each two pairs of turbines are provided with one gate shaft and the end of each gate shaft is provided with couplings for direct connection to a Lombard governor. The installation, as noted above, contemplates receiving the water in an open flume thoroughly protected by racks and discharging the water through central draft-tubes set vertically below each pair of wheels. The lower end of these tubes is to be at all times submerged at a depth of from 6 to 12 in. The tail-water will at all times show a depth of from 10 to 12 ft. in the channel below the bottom of the draft tubes. The turbines under a working head of 24 ft. will develop 2,800 H. P. at about seven-eighths of full gatage [sic] gauge. This gives a total capacity of 2,800 H. P. in each unit or 5,600 H. P. in all.
Two complete bulk-head casings, each 8 ft. in diameter, are provided and installed at either end of the generator room, separating it from the turbine rooms. Through these bulk-heads are extended the turbine shafts, which at this point are 10 in. in diameter. Also provision is made for carrying the turbine gate shafts through the same bulk-head. Suitable bearings are provided for all such shafts. Just inside of the bulk-heads in the generator room are installed the type "N" Lombard governors. These governors are located alongside the horizontal turbine shafts, to which they are directly belted. They are directly connected to one of the gate shafts, and to the other by means of wire-rope sheaves installed on the ends of the gate shafts. Each of these governors is provided with a suitable pump fitted with the necessary pipes and storage tanks for operating the governing mechanism. Two electrical speed controllers of Lombard design are attached to the governors for the purpose of synchronizing the speed of the turbine units at time of starting either generator.
ELECTRICAL EQUIPMENT IN GENERATOR ROOM.
The electrical equipment in the generator room is very simple. To each end of the turbine shaft is directly coupled the shaft of a 1500-K W., 3-phase, 25-cycle, 2300 volt, alternating-current generator designed to operate at 1872 rev. per min. A 55-K. W., 125-volt, direct-current exciter is directly belted to each turbine shaft. Each exciter is of sufficient capacity to provide current for both generators and at the same time supply the necessary current for lighting and small motors about the plant. These two generators and two exciters, together with the switchboard, constitute all the electrical apparatus installed in the generator room, the step-up transformers and high-tension switches being installed in the transformer house located on the bank of the river about 50 ft. south of the south end of the dam. As seen from the cut, Fig. 6, the switchboard is located on the up-stream side of the generator room about 42 ft. from the wall.
The generator field rheostats are installed in pits underneath and behind the switchboard. The current and potential transformers used in connection with the 2300-volt generators are installed in a pit of ample size underneath the generator. This pit also makes it possible to make any necessary repairs underneath the large generators. In the generator room is installed the 15-ton, hand-power travelling crane which greatly facilitates any small repairs that may be necessary in the generator room. The crane was furnished by the Whiting Foundry Equipment Company of Harvey, Illinois. All the electrical apparatus in the generator room and transformer house was furnished by the General Electric Company. The method of operation is at once evident upon consideration of the wiring diagram, Fig. 28, showing the connections between the apparatus installed in the generator room and the transformer house. The current generated in the generator room at 2300 volts is taken directly through a three-wire, paper-insulated lead-encased cable to the transformer house and led directly to the low-tension side of the transformers. From the high-tension side of the transformers the current is led through type "H" oil switches and single-pole disconnecting switches to the high-tension bus-bars, and from the bus-bars through single-pole disconnecting switches and type "H" oil switches to the line. The line is protected by standard General Electric lightning arresters. The type "H" high-tension switches installed in the transformer house are operated from the switchboard in the generator room by means of the General Electric Company's standard system of remote control. Leads are also brought back from the current transformers installed in the line circuits to the switchboard, where they are connected with ammeters on the line panel.
SWITCHBOARD.
The switchboard, Fig. 9, consists at present of five panels. There are two exciter panels on which are mounted ammeter, voltmeter, exciter rheostat and main switch. There are also two generator panels on which are mounted ammeter, voltmeter, and indicating and recording wattmeters for the 1500-K. W. alternators; also the remote-control switch for operating the type "H" oil switch installed in the transformer house. From the wiring diagram it is evident that the generator with its set of step-up transformers is operated as a single unit. At present there is only one line panel, on which is installed the remote-control switch and three ammeters, provision being made for installing two more line panels as occasion may demand. On a bracket is installed a synchronizing indicator with lamp; also a Tirrill regulator is provided and installed on a small bracket at the end of the board. The current for lighting the generator room is taken from the 125-volt direct-current bus-bars and is controlled by switches placed on the lower part of the exciter panel.
The electrical connections between the generator room and transformer house are all paper-insulated lead-encased cable laid in tile ducts. For each generator there is a 3-wire 600,000,-circular mil. cable, each laid in its own tile duct. Other ducts of ample size are provided. In these are laid the two-wire cables used for switch control and for instrument leads. There is as well a 125-volt line leading from the main switchboard bus-bars to distributing panels in the transformer house for furnishing light and power to small motor.
TRANSFORMER HOUSE EQUIPMENT.
In the transformer house, Figs. 12 and 13, are installed the six 500-K. W., 2300-33000-volt, water-cooled transformers, the necessary type "H" oil switches, the high-tension bus-bars, the lightning arresters and the necessary current and potential transformers. The building is constructed of hollow tile and is approximately 41 ft. long by 31 ft. wide. The part of the building containing the entrances for the high-tension lines, the lightning arresters, oil switches and high-tension bus-bars, is about 33 ft. high. The other part, separated from this by a brick wall and containing only the transformers and high-tension delta, is about 20 ft. high by 14 ft. wide. The general layout is seen in the accompanying cuts. The 2300-volt cables end in the ordinary discharge bells located on the side of the transformer room. The cables lead directly to the low-tension delta connecting with the low-tension side of the transformer. The high-tension delta is installed directly above the transformers. All the wire connections are made of No. 2 bare copper wire supported on Locke No. 311 insulators. The high-tension lines pass through wall insulators made by the Locke Company into the other part of the transformer house and pass directly to the type "H" oil switches. The oil switches are supported on the floor of the second story, the floor being constructed of concrete and steel. The bus-bar compartment, Fig. 14, is located directly beneath the switches and is built up of the hollow tile used in the building construction. Between the high-tension bus-bars and the switches are installed single-blade disconnecting switches.
For the outgoing line the leads pass from the high-tension bus through the disconnecting switch to the oil switch, thence along the ceiling to the opposite side of the room, then directly up along the wall back of the lightning arresters to the double-pole disconnecting switch near the high-tension entrance. The method of bringing the wires into the building is shown in detail in Fig. 27.
The entrance to the building is built up of slate panels mounted on strap-iron supports. The high-tension wire passes directly through an opening in the wall of the transformer house into this wiring compartment and downwards through a Locke porcelain insulator to a standard line insulator mounted on a bracket on the outside of the building wall. This insulator serves to take up all strain at the end of the line. The impendance [sic] impedance coils used in connection with the lightning arresters are formed by winding the conductor in the form of a spiral about 6 in. in diameter with 1/2-in. pitch, and placing these coils along the wall directly back of the arrester. This gives a very compact and simple layout.
At present only three type "H" oil switches are installed, one for each generator transformer unit and one for the line. Space has been provided in the design of the building for the installation of two more such switches when additional transmission lines are built. Space is also provided for the necessary future lightning arresters.
The circulating water for the transformers is drawn in from the river above the dam by means of a small centrifugal pump direct connected to a 125-volt, 2-H. P. motor, and after passing through the transformers is discharged through a pipe, the end of which is submerged below the tail-water. The difference in head under normal condition is sufficient to maintain the necessary circulation, the system acting as a simple syphon, but in order to start the syphon in operation and assure positive operation the circulating pump has been installed.
THE TRANSMISSION LINE.
The transmission line, as shown in Fig. 18, consists of three No. 4 bare copper wires supported on Locke No. 311 insulators. The wires are arranged in the form of a delta, the top insulator being attached by means of a ridge iron to the top of the pole. The two lower insulators are supported on a 3/4-in. x 44-in. x 5-ft. cross-arm. All insulator pins are provided with porcelain bases. The distance between wires is 44 in. A ground wire, consisting of No. 6 soft-drawn steel, is installed on the side of the pole about two feet below the bottom of the cross-arm. This wire is attached to the pole by means of a 38-in. x 3-in. lag screw and washers and is carried from pole to pole parallel to the transmission line wires. At every fourth pole a ground connection leads from the ground wire to the ground and is buried below the bottom of the pole. These precautions have been taken on account of the fact that the district through which the transmission line runs is subject to very severe electrical storms during a large portion of the year. It is hoped that carrying the ground wire so near the transmission line, together with its frequent grounding, may materially lessen the difficulties in the operation of the system. The standard poles are 35 ft. long with 7-in. tops, set 6 ft. in the ground, and this brings the lower wire of the transmission line to about 26 ft. above the ground, while the ground wire is about 23 ft. above the ground.
The transmission line is transposed about once every mile, the number of transpositions being so chosen as to make a complete turn in the delta in each section of the line, that part of the line between the power house and sub-station, or between any two sub-stations, being considered as a section.
The telephone line is installed about 6 ft. below the ground wire, this line being transposed every second pole. This is accomplished by using a Locke transposition insulator on every other pole and two Locke No. 12 telephone insulators on the intermediate poles. It is found that this frequent transposition practically eliminates induction from the high-tension line.
Wherever the line crosses the main tracks of steam roads, special cradles are installed, as shown in Fig. 19, composed of No. 4 steel wire, so designed as to prevent any broken transmission wire from reaching the ground. These cradles are very thoroughly grounded, which will result in tripping the automatic oil switch and throwing the broken wire out of commission in case any break should occur in the line. Similar protection has been provided in case it is necessary for the transmission line to cross other transmission lines or telephone lines. In the latter case, however, wherever it is possible, as in the case of the tansmission [sic] transmission line crossing a telephone line at right angles, two poles have been set as close as possible on either side of the telephone line, making it impossible for any broken transmission wire to fall on the telephone line.
SUB-STATIONS.
At present four substations have been installed; one near Galena, one near Joplin, one southwest of Webb City in the Prosperity mining district, and one north of Webb City in the Oronogo mining district. At each sub-station there is installed in the main transmission line a horn switch of special design, the arrangement being such that the transmission line on the side farthest from the generating plant may be cut off. This provision is made so that in case of difficulty on the line, no sub-station between the fault and the generating plant need be permanently put out of service. By opening this switch repairs can be made on the line, while all sub-stations nearer the generating plant can be kept in operation. Between Joplin and Webb City there is branch in the main transmission line, one line leading to the Prosperity sub-station and the other leading to the Oronogo sub-station. At this junction point, two air-break switches are installed, thus making it possible to cut either end of the line off from the main line leading to the dam.
Sub-station No. 1 is located near Galena, while that known as sub-station No. 2 is located near Joplin. These two sub-stations are each built of brick and are about 18 ft. square (outside measurement) by about 30 ft. high. The general layout is shown in Fig. 22. The line entrance is in every respect similar to that used in the construction of the transformer house at Lowell, and likewise similar lightning arresters designed for 30,000 volts are connected to the line just inside of the entrance. Three single-pole form "K" General Electric oil switches, provided with suitable mechanism for hand operation, are installed on the second floor of the sub-station. The operating mechanism is connected to the switchboard, which is installed on the lower floor in front of the transformers. The high-tension wires coming from the oil switches pass directly to the delta and thence to the transformers located on the lower floor. Three 250-K. W., 25-cycle, 30000-2300-volt, water-cooled transformers are installed in each sub-station. The switchboard, shown in Fig. 25, consists of one 30,000-volt panel controlling the incoming line and two 2300-volt panels controlling the outgoing secondary lines. From the 2300-volt secondaries of the transformers, leads are taken directly to the low-tension delta, which is carried on bus-bar racks mounted on the front of the transformers. From the delta lead-covered cables lead directly to the floor, and under the floor to the bus-bars on the switchboard. From the feeder line switches the cables are carried in conduits under the floor, thence up the wall and out through porcelain insulating tubes to the secondary distributing line.
The design of the sub-stations is made as simple as possible, there being provided only one high-tension switch for disconnecting the sub-station from the line. In case it is desirable to disconnect the line leading from the sub-station or the line going to the sub-station from the power house, it can be done by means of the air-break switch referred to in a preceding paragraph. An ammeter, voltmeter and recording wattmeter to give the total station output are mounted on the switchboard.
While the layout for sub-stations No. 3 and No. 4, which are located at Prosperity and Oronogo, is exactly similar to that of the two just described, the equipment is somewhat different. In the two preceding sub-stations, General Electric apparatus is used throughout. In sub-stations No. 3 and No. 4, General Electric high-tension switches are installed, but the remainder of the apparatus, including the transformers, switchboard, lightning arresters, etc., are of Westinghouse manufacture. The buildings, too, are of different design. In this case it has seemed desirable to build a structure which could be easily moved from one place to another, and to accomplish this a light steel framework has been designed and built in such form as will permit its readily being taken down, as shown in Figs. 23 and 24. The siding is of corrugated iron supported on angle iron and the roof of wood sheathing lined with fireproof material and covered with corrugated iron. The whole structure is mounted on concrete piers which also carry the weight of the transformers; the only weight necessarily carried in the building being the oil switches mounted on the second floor and the lightning arresters. With this form of construction, it becomes a very simple matter to take down the sub-station and move it to another point in the mining district in case the mines in the immediate vicinity become exhausted, resulting in a change in the center of distribution of the area supplied with power. In some cases this may be very desirable on account of the mining conditions peculiar to the Joplin district.
SECONDARY DISTRIBUTION.
Secondary lines are run from these sub-stations to the various mills served by the company. These lines are carried on standard 35-ft. poles. The arrangement of cross-arms is shown in Fig. 17. A 4 ft. 6 in. cross-arm is placed at the top of the pole and beneath it a 4-ft. 2-in. cross-arm. This makes it possible to carry two 3-phase lines on each pole. For secondary transmission bare copper wire or cable of requisite size is used, the sizes ranging from 4/0 down to No. 1, depending upon the load and the distance of the load from the sub-station. In case two lines are not to be installed at once, only the upper cross-arm is put in place, and the three wires of the transmission line first installed are arranged in a horizontal plane on this cross-arm. In case the second line is added, it simply becomes necessary to install the lower shorter cross-arm and the additional insulators. It is probable that when two lines are installed, the ordinary delta arrangement will be adhered to, although for practical purposes the inductive drop due to placing the three wires of the transmission line on one horizontal plane is not at all serious. %%For the secondary construction No. 20 Locke glass insulators have been used mounted on No. 8 Locke pins.** The cross-arms are 3/4 in. x 44 in.
TELEPHONE SYSTEM.
A private telephone system has been installed with phones located in each of the four sub-stations and in the generator room and transformer house at the dam. The telephones are very carefully insulated from the walls and insulated stools are provided to be used while talking over the phone. For lightning protection an ordinary 2000-volt lightning arrester has been installed on the telephone line just as it enters the building. The telephone line next passes through the ordinary telephone fuses and then through sneak-current coils, which are also grounded, and finally through the small lightning arrester on the telephone. A double-pole single-throw knife-switch is installed between the telephone and the sneak-current coil, thus making it possible to disconnect the telephone from the line. An extension bell is permanently connected to the line. This arrangement is made in order that the telephone may ordinarily be disconnected from the line and the attention of the operator can be attracted by means of the extension bell. The operator can then close the knife-switch, thus putting the telephone in service, after which the conversation can be carried on. This precaution is taken with the idea that the telephone itself may be protected from any accident that may happen to the line.
MILL EQUIPMENT.
The standard mill equipment might be said to consist of a 15-H. P. hoist motor, a to or 15-H. P. pumping motor and a 50 or 75-H. P. mill motor with, in some cases, a 75 or 100-H. P. compressor motor. In cases requiring motors of 50 H. P. or over, 2300-volt motors have been chosen. In such cases the motors are protected by automatic oil switches. Motors of smaller horse-power are 440-volt motors, and suitable transformers are installed for supplying current at lower voltage to all such motors. These motors are generally of the squirrel-cage type and are operated by the starting compensator. A typical 50-H. P. mill installation is shown in Fig. 32. A 2300-volt polyphase recording wattmeter is connected to the line at its entrance to the building. The large power motors operating at 2300 volts are each controlled by its own automatic switch. The tap from the main service box leads to the transformers, which reduce the voltage to 440 volts. Leads are taken from the secondary transformers to the starting compensators of the various 440-volt motors. In case a small amount of lighting is to be done, a single-phase transformer can be connected across one phase, and sufficient current for this purpose can be transformed to 110 volts.
The work of construction has been done under the immediate supervision of Mr. Wm. H. Rosecrans, Civil Engineer for The Arnold Company, who has been in charge of all hydraulic features of the work. Mr. P. L. Battey, Electrical Engineer for The Arnold Company, has superintended all the electrical construction work. Mr. George E. Hayler, Jr., of The Arnold Company, who acted as engineering contract agent in securing necessary data for the power installations in the mills now equipped, later resigned this position to accept the office, which he now holds, of Superintendent of The Spring River Power Company.
Since the completion of the plant above described The Spring River Power Company has commissioned The Arnold Company to design and construct a 2,000-K. W. auxiliary steam plant to be located at Varck, about 3/4 of a mile distant from the hydro-electric plant. This equipment will contain water-tube boilers with down draft furnaces, vertical compound engines and alternator units of the revolving-field type. Barometric jet condensers will be supplied with water from Spring river by means of centrifugal pumps. In keeping with the water-power plant everything will be the best for the purpose that money can buy and is being installed to produce power in the most efficient manner. This equipment will be made the subject of a later bulletin.
