Automatic Voltage Control of Electrical Systems

Abstract

THE problems which arise in connexion with maintaining the voltage of supply constant in electrical distributing systems have been closely studied by electrical engineers during recent years. The permissible variation allowed by the regulations is plus or minus four per cent of the “declared” voltage, but the average regulation is much closer; the houses near the supply station at times of maximum load are supplied at a voltage above the declared pressure and the few near the ends of the distributing mains at a voltage below the normal. The lamps near the supply station therefore give a better light and have a shorter life than the distant lamps. In a paper read by W. Kidd and J. L. Carr to the Institution of Electrical Engineers on December 7, methods of automatic voltage regulation and switch control were described. The city of Manchester is the first area to have complete automatic voltage regulation and it also has supervisory control for its main substations. By a careful application of automatically controlled regulators it is shown that the voltage on distribution networks can easily be maintained within the permissible limits. Manual control of voltage is never quite satisfactory and necessitates the uneconomic employment of additional labour. The installation of the regulating equipment gives better service to the public and removes a possible cause of complaint. It has to be remembered that a rise or fall in the voltage of one per cent increases or diminishes the light emitted by the lamp by about three per cent. Several diagrams are given showing methods of adapting existing transformers by means of automatically controlled tap-changing devices so that the voltage of supply can be kept constant at all loads.