Grace's Guide

1889. London Electric Supply Corporation, Deptford Station.

1889.

1889. 30th March.

1889. 1000 kW Ferranti alternator, dominated by the rope drive pulley

Sction through 1000 kW Ferranti alternator. The disc armature is on the right

Remarkably, Manchester's Museum of Science and Industry recovered and utilised a pair of the generating station's cast iron columns

Detail of columns

Section of the original 10,000 V cable and the spike which was driven through it in 1890 to demonstrate its safety. Stored in a display case in the reserve collection at Manchester's Museum of Science and Industry in 2014

Section of one of the original cables installed in 1890 for the 10,000V Deptford-London cable, on display at Amberley Working Museum

Close-up of original cable joint at Amberley Working Museum

1895. 1000 kW alternator driven by Plenty and Son 1500 hp engines

1895. 1500 hp condensing compound engines by Plenty and Son

1895. 1500 hp engines by Plenty and Son

1912.

1927. Extensions to the Deptford Power Station.

Later known as Deptford East (Low Pressure) Power Station.

See also Deptford East (High Pressure) Power Station and Deptford West Power Station.

1887 Designed by Sebastian Ziani de Ferranti for the London Electric Supply Corporation, located to the west of Deptford Creek on a site once used by the East India Company. The scale of construction was unprecedented; the design pioneered the concept of generating high voltage (10kV) AC power on a very large scale on a convenient site on the outskirts of the main area of consumption.

"The Directors of the Grosvenor Gallery Company decided that Ferranti’s plans were commercially practicable and in 1887 the London Electric Supply Company Limited was incorporated, with an authorized capital of £1,000,000 to construct a large generating plant at Deptford, with trans­mission and distribution covering a large area of London. Ferranti was appointed Chief Engineer and to him, at the age of 23, fell the complete technical responsibility of bringing this tremendous project to success. Fortu­nately, he was one of those rare engineers who are endowed equally with the broad vision necessary to conceive large-scale plans as well as with the detailed engineering abilities necessary for their practical realization. These qualities were allied with a burning enthusiasm for whatever work he was doing, and he threw himself into the project with unbounded energy."

The station was intended to supply central London on a large scale but the need to lay cables across the streets of numerous local authorities provoked a Board of Trade Inquiry which also highlighted concerns about the wisdom of concentrating so much generating capacity at a single site.

The company lost customers due to early teething troubles and the station was opened on a smaller scale than envisaged. However it was still the world's largest power station at the time.

All the parts for the first alternators were made in the Deptford Generating Station under the direction of Mr. Ferranti, some very large machine tools by Thomas Shanks and Co being installed in one of the bays.

1889 A steam pipe accident stimulated the engineer-in-chief, S. Z. de Ferranti, to develop the idea of pipe bends comprising multiple small diameter solid-drawn tubes united by flanges, to avoid the use of large diameter copper pipes with seams, on which he secured patent rights.

1895 Description in 'The Engineer' of existing and new plant at Deptford . A drawing shows seven main engine-driven alternators: two 225 kW Ferranti alternators driven by Plenty and Son 350 HP triple-expansion engines; two 500 kW Ferranti alternators driven by Hick, Hargreaves and Co 750 HP tandem compound engines; two 1000 kW 10 kV Ferranti alternators driven by Hick, Hargreaves and Co 1500/1800 HP vertical compound engines, and the latest addition, a 1000 kW Ferranti alternator directly driven at 156 rpm by a Plenty and Son engine conceived by Patrick Walter D'Alton of the power company. The Plenty engine was most unusual, comprising three vertical tandem compound engines coupled together and sharing the same bedplate (see illustration). The cranks were set at 120 degrees. The HP cylinders were 16.5" diameter, the LP cylinders 37", and the stroke was 26". Steam was admitted to the HP cylinders by piston valves, and the low-pressure cylinders are fitted with ordinary flat slide valves. Each pair of valves was driven by a single eccentric, and all variation of speed was controlled by means of Joy's patent gear, fitted into the body of each eccentric, by means of which the stroke of the valves was varied as required, by hydraulically forcing the centre of the eccentric into any position between full and mid gear. Unusually, the article mentions the colour of the new Plenty engines - bright green, with black and vermilion lining. The total weight of the alternator was 80 tons.

1910 Two 5000 kW turbines ordered from Parsons, to run at the low speed of 750 rpm. The design was compromised by the limited space available. The turbines proved to be troublesome and returned poor economy. Various modifications were introduced, and themuch-improved machines were still available for standby duty in 1934, by which time one had run 64,000 hrs and the other 112,000 hrs.

1912 Review

When the station was first started, some of the plant from the Grosvenor Gallery station was transferred to it. An alternator was driven by belt by three Marshall engines, each of which could be clutched to the generator as the load required. Two of the engines had a capacity of 250 HP each, and the other of 400 HP. At full load all three engines drove the generator, the belt of the 400 HP engine being 31in. wide. The other alternator was rope-driven by a 750 HP Corliss engine made by Hick, Hargreaves and Co. The generators were at that time the largest in use in Britain. The armatures were 8ft. 6in. in diameter, and the speed 250 rpm. Current was generated at 2500 volts and transformers were used to step it up to 10,000 volts. In 1889 two machines of twice this output were commissioned, rope-driven by two 1500 HP Hick, Hargreaves engines. These alternators were the largest in the world at the time they were built, and they were still operating in 1912.

Ferranti's original scheme would utilise a variety of generators, the largest being 10,000 volt 10,000 HP machines. The Ferranti alternators were actually designed and constructed and their Hick, Hargreaves and Co vertical engines built and delivered, but they were never put to work. The shafts were 36in. in diameter, the armatures were 46ft. diameter, and the alternator alone weighed 500 tons. The speed was to be 60 rpm. The positions which they would have occupied were taken by two 10,000 HP/7500 kW Brown Boveri and Co turbine-generators, supplying current for working the suburban traffic on the London, Brighton and South Coast Railway.

In 1912 the station provided four distinct supplies:-

• The original 85 Hz 10 kV supply for lighting, supplied by six Ferranti and BTH machines.
• 460 V & 230 V DC three wire system for power and lighting.
• 3-phase 6.6 kV 25 Hz AC supply for power and traction.
• Single phase 6.6 kV 25 Hz AC supply for the Brighton Railway.

The 6.6 kV supply was provided by four Dick, Kerr and Co 2500 kW alternators driven by reciprocating engines, and two 7500kW Brown, Boveri and Co turbine-alternators. The engine-driven sets were originally used to supply energy to the London County Council trams, and later on for the power supply of the first electrified sections of the London and Brighton Railway, and for some years ran in parallel with the LCC's Greenwich Power Station.

The Brown Boveri turbines were a combination of the Parsons reaction type with the addition of an impulse wheel and nozzle group control. They could provide 50% overload for half an hour. The alternators were the largest in operation in Britain at the time. The pole shoes of the rotors were provided with heavy copper damping windings to_reduce the pulsating field set up when the machines are giving a single-phase supply. Tirrill voltage regulators were used.

A large 2000 HP motor generator set made by British Westinghouse had recently been commissioned. Its motor was driven from the three-phase 25 Hz system on the traction side, and drove an alternator supplying single-phase 10,000 volt 85 Hz current. This allowed both sides of the station to be connected together when required, and the turbines used at their maximum efficiency and capacity. Ad well as being used at times of light load, it is employed at times of peak load in the lighting section.

The whole of the early switchgear, including the original oil switches, was designed by Mr. G. W. Partridge (he had become by 1912) chief engineer of the company, who was responsible for many other ingenious devices in the station.

The boiler-house contained 22 Babcock and Wilcox boilers and 10 Paxman boilers, with superheat and economiser equipment. Two more Babcock and Wilcox boilers were being added, and the total capacity would then be 760,000 lb. of steam per hour. Coal was brought in from barges on the Thames by a Temperley transporter.

The condensing water from the Thames was delivered through rotary strainers by two pumps, each with a capacity of 650,000 to 700,000 gallons of water per hour. There were three water-cooling towers for use should the strainers break down.

The Early Cables

See photos.

The Engineer's 1912 review including the following description of Ferranti's remarkable conductors: 'In those early days the knowledge of what was required for the construction of a successful extra high-tension cable was by no means what it is now, and that a workable cable could be made with the apparatus at command is a matter for wonder. It was not only made, but much of it is still in use after twenty-three years' working at a pressure of 10,000 volts. We were given a small section of a piece of cable which had only been taken up last year, and we give a facsimile of it in Fig. 2. There is an inner conductor of copper tube having a cross section of .25 of a square inch. Round this was wound in an ordinary lathe a layer of paper impregnated with Ozokerite wax applied under pressure. The thickness of this was about 1/2in., and over it was slipped a copper tube, also having a cross section of .25 of a squre inch. The whole was then passed through a die until the copper gripped the paper lightly, and the section was complete as far as conductors went, though it was subsequently armoured. The outer conductor was run connected to earth. These sections of cable could only be made in 20ft. lengths, so that an idea may be formed of the number of joints needed. There were thousands of them. The method of making them was to use a copper rod some 10in. long which was a tight fit in the hole in the inner conductor, to force it in until it had entered some 5in. into one of the ends of cable to be joined, then to force on the next section of cable. The plug formed the connection between the two lengths of inners. and the onters were joined by a sleeve. There were about twenty-eight miles of this cable laid in all, and at first much of it was run on the walls and arches of the South-Eastern Railway Company's line. Finally, however, it was all run underground. It was the pioneer of all high tension paper cables.'

Later Developments

1916 A German bomb was dropped on the station in the early hours of 25 August, putting the entire traction and industrial switchboard out of action. Thanks to the courage and ability of the engineering staff, the lighting supply was restored within 12 minutes of the explosion, and the railway and power supplies within 24 hours.

1927 Review

In addition to the local London 83 Hz single-phase load, the station also supplied 25 Hz single-phase and three-phase current to the Southern Railway at 6.6 and 11 kV respectively, and also direct current to local consumers. The capacity had been increased to 100 MW. The single phase lighting demand was met by three 4000 kVA and one 7500 kVA turbine-alternators generating at 2.5 kV, stepped up by transformers to 10 kV. The single pahse industrial and railway load was met by one 8.75 MW and one 15 MW TAs generating at 6.6 kV. Three 20 MW 11 kV and one 25 MW TA were to be installed to supply the Southern Railway. The new turbines' steam supply would be at 300 psi, 700 degF.

The original building, known as Deptford East, remained in use until 1957.

Two of the generating station's large cast iron columns were saved for preservation by Ferranti and stored at their Hollinwood works. When Ferranti vacated the works, they donated the columns to Manchester's Museum of Science and Industry (see photos). These two columns now reach up only as far as where the rails for the overhead crane would have been fixed, and there would have been an even higher section supporting the roof.

Good account of the early history here and here.

Photos of the Science Museum's scale model of a section of the proposed station here indicates the startling difference in size between the intended reciprocating engines.

See Also

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Sources of Information

• Wikipedia [8]