Abstract :
In designing electrical installations for large chemical factories, the following four major factors have to be considered. The area of the factory is often very large and there may be many widely separated buildings, the processes are continuous and there are long runs between stoppages, the heavy power demand has a high load-factor, and there are frequent additions and alterations to buildings and electrical systems. It is shown that a high-voltage distribution system is required, and that the methods and materials of good practice in the supply industry are in general suitable. Experience shows that it is inadvisable to ¿tailor¿ an installation too closely to a body which is likely to have grown before the ¿suit¿ is much worn. The internal wiring and the electrical equipment of factory buildings having good clean conditions are discussed in some detail; it is claimed that the majority of the motors can be of the squirrel-cage type, directon-line started, and that contactor-type air-break starters are preferable to oil-immersed ones for their control. To combat corrosive and explosive hazards as much of the electrical equipment as practicable is installed outside the danger zone and the remainder is specially chosen for these conditions. A note is included on the effect of static charges on inflammable substances and inert powders, and mention is made of some methods of preventing the accumulation of a dangerous charge. The standardization of equipment and layout is briefly discussed.
