The Company is now planning for an annual output of a million kilowatts of generating plant, more than three times the average for the last twenty years.

GENERATORS
The design of turbo-generators has made steady progress. Today the efficiency of the largest machines made by the Company is 98.5 per cent, and the weight per kVA 4.5 lb, compared with 93 per cent and 12.5 Ib in 1914. The present year saw a great advance in British practice when a 75,000-kVA generator was put into service at Littlebrook. This was the first main generator to employ hydrogen cooling and the first 3000-r.p.m. machine of its size in this country; its testing in the works at full kVA rating was one of the largest wattless load tests ever carried out. The stator, which weighed 128 tons, presented a difficult problem to the works traffic department as it had to be taken by road for a total distance of 280 miles. Six similar machines and one of 66,600 kVA, all hydrogen cooled, are now in hand.

Separately driven exciters, which are sometimes preferred, have been provided with flywheels to maintain full load excitation for a few seconds if the supply should fail; in some sets the motor is transferred automatically to another source of current, or the exciter has two motors, each connected to a different supply.

Waterwheel generators made for Karapiro (New Zealand) are the largest in output and those for Tainionkoski (Finland) are the largest in diameter of any built in Great Britain. The Karapiro machines, three of 33,333 kVA at 167 r.p.m., were installed in 1948. Each had a rotor weighing 180 tons complete, and the largest piece weighing 148 tons was the biggest lift ever taken by the works cranes; the Company also designed the thrust bearing, which is 7 feet in diameter and has to carry a load of 750 tons. At Tainionkoski three 18,000-kVA 75-r.p.m. generators will have been installed by the end of this year.

Other large electrical machines in hand include the twenty-first 20,000-kVA synchronous condenser for the Victoria Falls Company's system and a 40,000-kVA unit for Australia; six of 30,000 kVA are being supplied for Spain, and another has been sent to Russia. These are believed to be the only 1000-r.p.m. condensers of their size. A frequency changer of 31,250 kVA was recently supplied for the interconnection of the 40-c/s and 50-c/s systems in Western Australia.

In Diesel-electric ship propulsion a striking advance was the use of a single set of Diesel-generators to supply all the power requirements of the ship. This was done for the first time on three dredgers recently put into service on the Mersey; the equipment is based on a metadyne-controlled constant current circuit, into which each of the main motors and deck machinery motors can be inserted in series.