The distribution of electricity

The principal conditions of economic distribution are determined by conflicting technical and financial considerations. Certain approximations are shown to be possible which assist in deciding the principal technical conditions. The necessity for several working pressures is shown. A general expression is obtained for capital expenditure on mains and substations. The effect of load factor on losses is considered and a formula, established for general use. The cost of supply is analysed and appropriate expressions obtained. The approximations reached enable Kelvin´s law to be applied to decide economical current densities and pressure-drop. A consideration of expenditure on a power distribution network indicates a method of arriving at the economical number and size of substations. The special considerations accompanying the use of high-pressure cables and of overhead lines are enumerated, and the method of arriving at the economical working pressures for various parts of the system is shown.