Heavy current transformers with three-phase ratings up to 6000 kVA 20,000 A have been made for arc furnaces used for the production of special steels. The tappings are controlled by a motor-operated off-circuit tap changer on the high voltage side.

Heating with infra-red lamps has been applied successfully to a wide range of processes in various industries, notably the boot and shoe trade.

Tubular-sheathed heating elements are made in lengths up to 8 ft and can be equipped with various heat-resisting sheaths, including one to withstand temperatures up to 800°C. They have been developed for many industrial heating applications, among the most successful being the electrical heating of large stereo-metal pots in newspaper foundries; the first of these equipments was supplied to a Manchester newspaper in 1939. The latest application of tubular-sheathed elements is for infra-red heating: compared with infra-red lamps they give a longer wavelength and greater intensities, which are an advantage in some processes. A range of sheathed element infra-red heaters with reflectors has been developed.

LIGHTING
The design of lighting fittings made a good start in 1938 with the Trafford streetlighting lantern, designed to house a 400-watt mercury discharge lamp burning horizontally. The Trafford was the first British-made lantern with an enclosed refractor bowl, and its daylight appearance, the importance of which is sometimes overlooked, has received the blessing of the Royal Fine Art Commission; it is now recognized as a standard type in its field. A complete range of industrial fittings was developed to match the 80-watt fluorescent tubular lamp put on the market in 1940, and these have been installed by factories all over the country. Other fittings were produced to correspond with the new lengths of lamp introduced after the war, and the series has been extended to the more decorative types for nonindustrial use.

In 1948 the research staff and lighting engineers produced the 'SO Fifty' streetlighting lantern, which breaks away from conventional design, being made almost entirely of Perspex. The SO Fifty is believed to be the first all-enclosed lantern of the bowl refractor type for sodium lamps, and, like the Trafford, it has been passed by the Royal Fine Art Commission.

The Company's engineers have collaborated in the design of many large lighting installations, both industrial and decorative. Outstanding among them are the pioneer fluorescent lighting in the public rooms of the liners Orion and Orcades and the lighting of Wembley Pool and Stadium, where special fittings were developed for the different sporting events.