Remote control of power networks

Brief introductory remarks in Section (1) draw attention to the fact that modern centralized indicator equipment isessential for the economical operation of power distribution networks. The type of equipment described in the paper is covered by two definitions, namely centralized indication equipment and supervisory control equipment. The various facilities usually demanded in practice are outlined. The choice of method and type of signalling channel to be usedare discussed, and the need for adequate protection of the signalling channel and equipment against possible high induced voltages is emphasized. A schematic diagram of typical protective apparatus is given. Section (2) contains an outline description of Strowger automatic telephone apparatus, which is employed on the various schemes of remote supervision and control described in the paper. The characteristics of telephone type relays, polarized and non-polarized, and the operational features of the uniselector (rotary switch) and two-motion selector mechanisms are outlined. The symbols employed in the diagrams are indicated. In Section (3) the layout of centralized control rooms is discussed, with particular reference to the various types of wall and miniature diagrams employed. The layout of certain control rooms of the British grid systems are given. The operation of typical circuits employing the uniselector for the remote indication of switch position is described in detail in Section (4). The function of the repeat relay in ensuring that the indications displayed are in accordance with the actual conditions prevailing, is outlined. The various methods of remote metering, including individual selections, spot readings, and photo-telemetering, are described in Section (5). The operation of a system of engine-room telegraph signals is described in Section (6). Section (7) deals with a system of protection of power networks over the signalling circuits by means of automatic telephone apparatus. Characterized- by extreme rapidity of operation, with automatic self-checking features, this system is shown adapted successfully to the inter-tripping of circuit breakers. The operational features of the fundamental circuits are described in Section (8), including the processes of selection, proving the selection, remote control of selected item, and the subsequent signalling of the indication that the intended operation has been effected. In Section (9) are described the methods of a.c. voicefrequency signalling employed in circumstances where the length of line or make-up of the signalling channel prohibits the employment of d.c. signalling. The paper finishes with a Conclusion and a Bibliography.