THE COLLIERY GUARDIAN AN® JOURNAL OF THE COAL AND IRON TRADES. _______________________________________ Vol. CXVI. ________________________________________________________________________________ The Britannia Colliery, Pengam, Mon.* By GEORGE HANN. The Britannia Colliery, recently sunk at Pengam, Mon., by the Powell Duffryn Steam Coal Company, differs from the ordinary in two respects, the whole of the machinery being electrically driven—there are no steam boilers at the colliery—and the whole output being got by conveyors. There are no horses, the haulage being mechanical throughout. Surface Equipment. The colliery is situated 1| miles to the south of Bargoed Colliery and three miles from Penallta Colliery. Both these collieries had power available in the shape of exhaust steam from winding engines, compressors and fans, and Bargoed Colliery also had surplus gas from the coke ovens. This was perhaps the main consideration which decided on electric power as the drive for the machinery, the other factor being that the site of the pits was confined, and the elec- tric equipment took much less room, as boiler house, cooling pond, etc., were not required. To supply the power for the new colliery during the sinking, -2-3,000 kw. mixed pressure turbo- generators were put in at Penallta Colliery, each turbine being capable of developing 1,750 kw. on exhaust steam. The generators are 10,000 volt machines, three-phase, 50 periods, and the power is transmitted at this pressure to Britannia on two FRIDAY, JULY 26, 1918. No. 3004. bouring collieries, and so it was determined to adopt the Ilgner system, which reduced the maximum call on each winding engine to 1,750 horse-power when winding six tons from the above depth each minute, with guaranteed consumption of 22 units per wind, or 360 tons per hour for 1,325 units. Two Ilgner sets were put in, each consisting of one fly-wheel 30 tons; (1) 10,000 volt A.C. motor, (2) variable voltage dynamos. The 10,000 volt motors are fitted with air filters to ensure their being supplied with clean air, and so avoid the troubles of over-heating due to the ventilating ducts becoming blocked with dust. The two sets were placed in line and connected by a fric- tion clutch; friction clutches were also provided between the fly-wheels and V.V. dynamos. The arrangement makes it possible to run either one or both fly-wheels writh either. Ilgner set, and has the advantage that, when both winding engines are work- ing, a better balance is obtained by running the two Ilgner sets coupled than by running them dis- connected. The foundation for this combined set, with a total over-all length of 102 ft., required to be carefully con- sidered, as the workings in the house coal seam belong- ing to a neighbouring colliery company had worked to within a short distance of the shafts. It was finally decided to place those Ilgner machines on one ferro- power from a rotary converter of 1,100 kw., which also supplies power to a fan motor of 550 horse-power. Ventilating Fan. The fan is of the “ Indestructible” type and has a duplicate drive, the main drive being by the con- tinuous current motor of 550 horse-power with speed variation from 70 to 135, and by an A.C. motor driving by means of ropes. On both sides of the fan shaft friction clutches are fitted to enable either motor being put on load without reducing the speed of the fan. Power Consumption. The number of units consumed weekly at the be- ginning of 1917, when the output, 10,158 tons for the week, could be raised by one Ilgner set, was 282,600. The coal consumption per unit at Middle Duffryn Power Station is 2| lb. per unit, and applying this figure to the Britannia Colliery, viz., 282,600 x 2| lb. = 315 tons of coal, or 3-1 per cent, of the output. Table A gives the amount of power used by the different machines and percentage of consumption to output:— Table A.—Output for Week ending January 13, 1917— 10,158 tons of Coal (gros«). Percentage Plant. Units consumed. Average load.* of output consumed. Pumping . 101,480 604 .. ....... 1'11 Compressed air ... 90,150 .... 536 .. 0 99 Winding 68,800 .... 410 .. 0'75 Ventilating 15,000 .... 90 .. 0T7 Miscellaneous 7,170 .... 43 .. 0'08 Total 282,600 ... 1,683 .. 3'10 * Based on 168 hours per week. Fig. 1.—Section through Power-House and Air-tight Casing. 8 twsi overhead lines, each of 0-25 square inch section, both lines being on the same poles. From the gas engine station at Bargoed two separate lines of similar size on separate poles were erected. In addition, during 1916 a 30,000 volt line was erected to connect the Britannia Colliery to Middle Duffryn Power Station, at Aberdare, owned by the same company. The length of this line is nine miles, of which one mile is cable and eight miles overhead construction. This line is now in use, and the colliery therefore served by three power stations with five separate feeders. .This 30,000 volt line was also for linking up the power supply systems at the collieries in the Rhymney and Aberdare valleys, the whole of the Powell Duffryn collieries being thus inter-connected. The peak loads over the whole system run up to 16,000 kw., with an annual production of 75,000,000 units. The arrangement of the switchboard at Britannia was a matter of great importance, for a failure at that point might have cut the colliery off from all sources of power. The board was constructed with a ring bus-bar and divided into two sections by isolating switches, one line from Penallta and one line from Bargoed being connected into each half. The switch gear is below the engine house floor level, and is operated by mechanism from above. A similar board is provided for controlling the 3,000 volt machines. Owing to the great depth of the shaft, viz., 730 yards, and the provision for a large output, 360 tons per hour from each shaft, the power of the winding engines at its maximum amounted to nearly 5,000 horse-power. This was too great a load to be carried satisfactorily by the generating plant at the neigh- * From a paper presented to the South Wales Institute of Engineers. concrete bed, which was designed to support the machine with but slight deflection should there be any subsidence. Winding Engines. The winding engines consist of a spiral drum 14 ft. to 22 ft. in diameter, to which a motor of 2,000 horse- power is directly coupled on each side, so that in case of the failure of one motor, it is still possible to wind with the other motor at a reduced speed. The exciters for the winding engine are two in number, and are separately driven by A.C. motors. There is also a storage battery of 117 cells, which provides the exciting current if the power supply fails. This made it possible to raise the sinking hoppit with the power stored in the fly-wheels, which was an important point during the sinking period. The battery also provided an emergency lighting in the case of failure of the power supply. Air Compressors. For supplying compressed air during the sinking, two fast running air compressors, driven by A.C. motors, were put in, their capacity being 2,500 cu. ft. free air, and 3,500 cu. ft. free air per minute at 75 lb. pressure. These engines ran at a speed of 280 and 250 r.p.m. and were constant speed, the supply of air being varied by an unloading device. Since then a 6,000 cu. ft. air compressor, running at 210 r.p.m., driven by an A.C. motor of 1,000 horse-power and fitted with a phase advancer to improve the power factor, has been added, as well as a low speed 105 r.p.m. horizontal compressor of 5,000 cu. ft. free air per minute, driven by a continuous current machine with speed variation down to 58 and an unloading device below this speed. This motor is supplied with The figures at a later period are not so favourable, as the output soon after had increased to a point at which two Ilgner sets had to. be run, but as the output increases further, the units for winding will again reduce to the former level per ton. Also, the colliery worked short time owing to lack of tonnage, the only full week’s work over a long period being the week ending November 24, 1917, and the figures for this week are as follow : — Table B.—Output for Week ending November 21, 1917— 12,529 tons of Coal (gross). Percentage Plant. Units consumed. Average load.* of output consumed. Pumping........ 134,490 ..... 800 ..... 1 2 Compressed air ... 150,030 ............. 893 ..... 1'34 ..... ..... Winding........ 94,440 ..... 562 ..... 0'84 Ventilating ..... 16,080 .... 95 ..... 0'14 Miscellaneous ... 11,260 .... 70 _____ OTO Total __..... 406,300 ..... 2,420 ..... 3'62 * Based on 168 hours per week. This may not appear to be a very good figure, but it must be remembered . that the pumping load is very heavy, and the whole of the coal is conveyed and hauled by compressed air, which absorbs 893 kw. per hour throughout the week. VRth a further increase of output these figures should W improved, as the. pumping load will be spread over a larger output. The compressed air will probably not increase, although the haulage distance will increase, as more will be done by electric power. The winding engines will be working nearer their maximum load, and the units per wind will be less. It is submitted that these figures fully justify the’ complete electrification of collieries, and there appears