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May, 1935

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It now remains to discuss the electrification of the remainder of the surface equipment and to recount the changes that have been made belowground.

Ventilation

No change has been made to the ventilating plant itself, although the steam-engine drives have been replaced by electric motors. Duplicate Waddle fans are in service, each 33 ft. 6 in. in diameter and rated to deliver 250,000 cu. ft. of free air per min. against a pressure of 6 in. w.g. One of these fans is gear driven, the other being driven by rope, and each is served by a G.E.C. 450 h.p. 2,750 V. 472 r.p.m. dual-frequency reconnect-type induction motor controlled by a liquid starter. There is also a Sirocco 84-in. 150,000 cu. ft. per min. 2½-in. w.g. fan for reverse ventilation, but it has not been necessary to convert this to electric drive.

Compressed air

Prior to the reconstruction the motive power belowground was compressed air. About 13,000 cu. ft. per min. was required, and considerable wastage occurred due to transmission and to the use of old and inefficient machinery. Electricity has now been substituted for compressed air throughout the workings except for a few districts that have a short life. To serve these districts about 3,000 cu. ft. of air per min. is required, and this is supplied by duplicate Belliss & Morcom compressors, one acting as standby to the other, each rated to compress 3,500 cu. ft. of air per min. to 80 lb. per sq. in. Each compressor is driven by a G.E.C. 585 h.p. 2,750 V. dual-frequency reconnect-type induction motor, which is controlled by a liquid starter interlocked with the main switch. These units are depicted in Fig. 24.

Coal preparation plant

For many years the colliery has supplied Wallsend best, nuts, peas, pearls, and duff coals, these sizes being made in a Grange Iron Company's (County Durham) screening plant. Coal above 2½ in. is sorted on picking belts, and that from 2½ in. down to ½ in. is cleaned in a Greaves washer. A first step in the colliery reconstruction was the addition of a Birtley dry-cleaning plant, having a capacity of 60-100 tons per hour, to handle coal below ½ in. This plant was erected in 1931, and was fully described in our July, 1932, issue, so that no further account is necessary. The Birtley plant has, of course, been electric ally driven from the outset, but the screens and Greaves washer were steam driven and have been converted to electric drive. The screening plant is driven by squirrel-cage motors of comparatively small denomination; a 65 h.p. slipring motor serves the washer, in conjunction with a 25 h.p. squirrel-cage direct-starting pump motor and a 25 h.p. slipring motor driving a scraper conveyor for the washed nuts and peas.

The remainder of the surface plant calls for little comment. Various repair shops and other departments have squirrel-cage motors ranging from I to 25 h.p., and there is a 75 h.p. slipring motor serving the stone heap haulage.

Underground equipment

Below ground the outstanding feature has been the reorganisation of the haulage system. As will be seen from the plans of the pit cable roads given in Fig. 25, the haulage system is elaborate; it replaces a system of compressed-air haulages, many of which were old, inefficient, and installed at considerable distances inbye, and the power cost for the electrical system has proved to be only 20 per cent, of that of the compressed-air system, and, in addition, maintenance charges are less.

The largest haulage is a 350 h.p. main-and-tail unit in the South pit, this being followed by four haulages of 250 h.p. — two main-and-tail units in the West pit and one main-and-tail and one endless in the Harvey. The 350 h.p. and 250 h.p. haulages are controlled by liquid controllers, with gate-operating gear and oil-immersed stator reversing switch. Then come six haulages of 100 h.p. capacity, one of 75 h.p., five of 50 h.p., and three of 25 h.p. The 100 h.p. and 50 h.p. motors are controlled by oil-immersed contactor-type stator reversers and liquid controllers, the 25 h.p. motors being controlled by drum-type oil-immersed stator starters and liquid controllers. The mechanical portions of these haulages were built by Jos. Cook, Sons & Co. Ltd., the electrical equipment being, of course, of G.E.C. manufacture. A 100 h.p. haulage working in the Harvey pit is shown in Fig. 19.

Electrical operation is also being applied to the coal face. In the Harvey seam, which is 3 ft. in thickness, a double-unit face has been developed, giving a daily output of 300 tons. British Jeffrey-Diamond and Anderson Boyes coal-cutters make a cut of 4 ft. 6in. over a face length of 200 yards, the coal being brought down by blasting, the shot holes being drilled with a Siemens-Schuckert electric drill and loaded on to Hugh Wood face conveyors, which deliver to a Hugh Wood gate conveyor. This equipment is served by the G.E.C. gate-end boxes depicted in Fig. 20. A second double-unit face, providing 400 tons per day, is also in course of preparation in the Harvey seam, the equipment comprising Sullivan and Anderson-Boyes coalcutters making a 4 ft. 6 in. cut over a length of 260 yards, and Hugh Wood face conveyors and gate conveyor.

The pumping duty for the mine is allotted mainly to a Uskside three-throw pump delivering 300 g.p.m. against a head of 1,830 ft. and driven by a 250 h.p. motor. There is also a Mackley 350 g.p.m. 320 ft. head centrifugal staple pump. This staple is sunk in the pit yard 24 fm. deep, and the water is used for the coal-washing plant, winder controllers, &c., this pump being served by a 56½ h.p. motor and controlled by an automatic starter. The remaining pump is a Mackley three-throw 50 g.p.m. 210 ft. head unit driven by a 6 h.p. G.E.C. motor in the South pit.

Distribution system

The electrical distribution system is given in full in Fig. 18, and the cable layout below ground in Fig. 25. Power is brought to the colliery at 11,000 V. and transformed by the North-Eastern Electric Supply Co. Ltd. to 2,750 V., this supply feeding into an ironclad main switchboard consisting of oil-immersed drawout circuit breakers of 50,000 kVA. rupturing capacity. As will be seen from the circuit diagram, Fig. 18, the incoming feeds and bus couplers divide the switchboard into two sections, the right-hand section controlling the winders and fans and the left-hand section (depicted in Fig. 21) controlling all other supplies. Each winder has its own feeder, but the winder boards are coupled together to form a ring main, enabling any winder to take its supply from any feeder. The supply for the gear-driven Waddle fan is also tapped off this ring main, the rope-driven fan having an independent feeder. The left-hand section of the board supplies three pit feeders, two feeders to the air compressors, and a feeder to the stone heap haulage and the staple pump. Two feeders are also taken from this board to two 500 kVA. G.E.C. transformers supplying a low-tension main board at 440 V. This board is also of ironclad oil-immersed drawout construction, the rupturing capacity of the units in this case being 25,000 kVA. Feeders are taken from this board to the screening plant, from which a supply is also taken to the Birtley dry-cleaner, to the tub shop, which acts also as a distributing centre for the sawmill, pugmill, lamproom, pick shop, and cage shop, and to the smiths' shop and fitting shop.

Below ground there are three substations, the Maudlin, the Hutton and the Harvey, the last-named being illustrated in Fig. 22. Two of the pit feeders are taken to the Maudlin substation and the third to the Harvey, the Hutton substation being interlinked between the others to form a ring main. Almost the entire underground equipment is served at 2,750 V., but individual transformers stepping down to 440 V. supply the 25 h.p. haulages and the 6 h.p. Mackley pump. Numerous lighting transformers giving a supply at 110 V. are scattered about the workings in strategic positions, and the mechanised faces have local transformers stepping down to 440 V.

The distribution scheme involved the installation of 16,800 yards of Pirelli-General cable, comprising 2,800 yards on the surface and 14,000 yards underground. The pit feeders are a special form of shaft cable of 0.2 sq. in. cross section, and of paper-insulated lead-covered doublewire-armoured construction. Over one hundred motors have been installed, totalling about 8,000 h.p.

We are indebted to Mr. George Hindson, Agent of The Ryhope Coal Co. Ltd., for his kind permission to publish this article, and would tender him our best thanks for his valued co-operation.

Drawings and Photographs accompanying the article