Portsmouth Electric Supply Works
of Gunwharf Road, Portsmouth
The area of supply was initially limited to the County Borough of Portsmouth, which at that time comprised only a part of Portsea Island.
Portsmouth Municipality was the first public authority to employ a steam power plant in its power station (the electricity companies in Newcastle and Scarborough having already used this technology). The 150 kW turbine-generator was installed alongside two 212 kW units with reciprocating engines, and provided the first demonstration of the ease with which slow-speed engine-driven alternators could be operated in parallel with slow speed engine-driven alternators. The alternators were Ferranti's first with a revolving field (rather than stationary field and revolving armature).
1894 'THE ELECTRIC LIGHT AT PORTSMOUTH. DESCRIPTION OF THE WORKS.
This afternoon the Mayoress of Portsmouth (Mrs. A. L. Emanuel) inaugurates the electric light the borough by formally starting the machinery at the generating station Gunwharf-road, and this evening the main thoroughfares will be brilliantly lighted by the new illuminant.
History of the System.
After obtaining an Electric Lighting Order from the Board of Trade, the Corporation appointed a Committee to go into the whole question and report as to the advisability of introducing the light into Portsmouth. Alderman Ellis, J.P., was chosen Chairman, and throughout he has been most indefatigable in his exertions to secure the success of the installation. The Committee obtained professional advice upon the subject generally. The first scheme suggested was a low-tension continuous current system, but although that had many advantages, it was felt that it would not adequately provide for the requirements of a town extending over such a large area as Portsmouth. The Committee therefore called in Professor William Garnett to report on the high and low tension systems, and that gentleman having given his opinion, decided in favour of the former. The matter was once more laid before the Council, who consented to the abandonment of the old system and the carrying out of the new scheme, and Professor Garnett and Messrs. Waller and Mauville were appointed to act as joint engineers to the Corporation.
The technical name of the system adopted is the high-tension alternating-current transformer system. As it gave ample latitude for the selection of site, it was determined to choose one in proximity to the harbour, so that economy in using condensing engines might be obtained. A suitable position was ultimately found in the site of the old music-hall in Gunwharf-road, and in the land adjoining. Here some very spacious buildings have been erected, consisting of a boilerhouse, an engine-house, coal store, and offices over the coal store. The engine-house is 102 ft. 6in. long by 66ft. wide and 32ft. high, and is spanned by travelling crane, which traverses the building from end to end. Immediately outside of the coal store is the chimney shaft, which is 120 feet high and 6ft. square inside the base.
So much for the building, which extends from Gunwharf-road to St. Mary's-street.
We now come to the machinery, &c. In the boiler-house there are five Lancashire boilers, fitted with all the most modern appliances for saving labour. They are fitted with Vicar's mechanical stokers and furnaces. Fine dust coal is conveyed in buckets or hoppers, moving in succession an elevator. On arrival the top of the elevator, the contents of each hopper are discharged into an overhead trough that runs the whole length of the boiler-room, and, manipulated by revolving screw, the fuel passes along until certain apertures are reached, through which is dropped into the mouth of each furnace. The shifting double bars of the furnace push out the exhausted cinders. All the labour neaded this department is that of a man and a boy. The steam pipes leading to the engine-room are in duplicate, so as to afford resource in case of a breakdown, and the steam pumps that supply the boilers have also been duplicated. Two large pipes are used to bring the sea water from the Camber, distance of 256 feet, for condensing purposes.
The most interesting feature is the engine-room, and without attempting to give anything like a technical description of the machinery, it may be said that three dynamos have been fitted up, and provision has been made for a fourth, so soon as it is required. The four sites occupy only half of the floor-space, so that there is plenty of room for extension. The two principal engines are the invention of Mr. S. Z. Ferranti, of London, who has personally superintended their construction. The idea is to economise space and power, and this has been accomplished by placing alternating current dynamos on the huge fly-wheels (each of which measures 14ft. in diameter) of the engines. These combined engines and dynamos are run at slow speed — 96 revolutions a minute — and each dynamo is capable of furnishing current to supply about 6,000 10-candle power incandescent lamps. The third engine is one of Parson's turbo-generators, a machine of a much more familiar type. It works upon quite a different plan, and runs at the high speed of 3,000 revolutions minute. So far it has produced excellent results. The current is taken from the dynamos to the switching gear by means of insulated cables. The switching gear is also a new invention of Mr. De Ferranti, and it has been designed so as to be as simple as possible, and is altogether different and far superior to the complicated gear at most stations. From the switching gear the cables pass through recording instruments which trace lines upon sheets of paper and show the pressure and quantity of the current at all times of the day and night. There is, therefore, a permanent record of what the station has been doing, at any time, and which can always be referred to.
The Public Lighting.
The area for the public lighting extends through High-street and Kings-road to the end of Elm-grove through Palmerston-road, Osborne-road, and Hampshire and King's terraces, Southsea, along the sea front, from Southsea-terrace, via Clarence Esplanade, to the South Parade Pier, and there are arc lamps on the Esplanade between the two piers. The area also includes in the other direction Commercial-road as far as All Saints' Church, Queen-street, Portsea, and The Hard. Altogether about 25 miles of insulated cable have been laid down in cast-iron troughing, on what is known as the Johnstone system of conduits. There are 101 arc lamps for street lighting purposes. They are of the latest pattern, having duplicate carbons, the second coming into use automatically should the first give out. The arc lamps will be switched on every evening at dusk, and they will continue alight until midnight, when they will switched off, and the two incandescent lamps that have been fitted on each of the standards will then be turned on and will continue alight until sunrise. Hitherto the current for the supply of this kind of arc lamp has been obtained by separate arc-lighting dynamos and engines, which run at high speed and require a great deal attention, besides consuming large amount of fuel. But here again Mr. Ferranti's skill came to the rescue, and the Committee wisely adopted his system of motor commutators, which take the ordinary alternating current supplied for incandescent lighting, and transform into continuous current of the necessary pressure and quantity for supplying the arc lights. By this means the extra small engines and dynamos have been done away with, and although the lamps by which Portsmouth is lighted are far more powerful than those in the streets of any other town, this result, owing to Mr. Ferranti's invention, has been obtained at a considerable less cost than in other towns. Another important merit of the system adopted is the facility for lighting exceedingly large district, and that with no diminution of brightness at even the furthest point from the generating station.
The electricity for supply to private consumers passes into the streets at 2,000 volts, but it will be transformed down to a pressure of 100 volts, and then supplied to the consumers through low-tension mains. The boxes containing the transformers are of cast-iron, and are placed in brick chambers, constructed beneath the pavement level at frequent intervals. From these transformers the low-tension wire system is fed. Mr. De Ferranti has also designed an apparatus by which great saving of electricity is effected in the transforming, so that instead of being able to sell not more than about 60 per cent, of the electricity generated, the remainder being wasted, at Portsmouth the Committee will have 90 per cent, of the electricity for disposal. The result will be a great saving in producing the light.
The work has been carried out by the following contractors: —
Buildings, Mr. T. W. Quick, Southsea ; boilers, mechanical stokers, engines, alternators, electrical apparatus, switch-boards, transformers, instruments, &c, Messrs. Yates and Thom, of Blackburn, and Messrs. S. Z. De Ferranti, Limited, London ; turbo-alternator and condensers, Messrs. C. A. Parsons and Co., Newcastle-on-Tyne ; conductors and junction boxes, the International Electric Subway Company, Limited, London, and Messrs. W. T. Glover and Co., of London and Manchester.' 
1898 the electricity generating capacity was 1.386 MW.
By 1914 the output capacity of the plant was 3.3 MW.
Post-WWI A new plant was installed in place of the original station, using three-phase, 50 cycles/s generation; this was inaugurated at the end of 1922; total generating capacity was 9.65 MW.
1927-9 New low pressure (LP) generating sets were commissioned, consisting of:
- 1 × Babcock CTM 88,000 lb/h, operating at 250 psi and 650 °F (11.09 kg/s, 17.2 bar and 343 °C)
- 2 × Babcock & Wilcox CTM each 50,000 lb/h, operating at 250 psi and 650 °F (6.3 kg/s, 17.2 bar and 343 °C), the boilers supplied steam to:
- Turbo-alternators: 2 × GEC /Fraser and Chalmers 10 MW sets, operating at inlet steam conditions of 245 psi and 700°F.
1938-52 High pressure (HP) plant was commissioned in stages: August 1938, September 1941, December 1948, and March 1952, consisting of:
- 2 × Clarke Chapman marine type each 123,000 lb/h, (15.5 kg/s)
- 5 × Bennis quadsum each 165,000 lb/h, (20.8 kg/s)
- 2 × Mitchell each 180,000 lb/h, (22.7 kg/s)
- Turbo-alternators: 4 × British Thomson-Houston 30 MW sets, operating at inlet steam conditions of 245 psi and 700 °F.
1977 The station was closed and disconnected from the grid.
Sources of Information
- The Engineer 1894/08/03 p104, p107, p109 and p122-3
- 'The Early Days of the Power Station Industry' by R. H. Parsons. 1939, Babcock & Wilcox, Cambridge University Press
- Portsmouth Evening News - Wednesday 6 June 1894
-  Wikipedia