Chapter 2 - Drawings and Diagrams

Abstract

This chapter describes different types of electrical diagrams. It explains how the diagrams are developed from original concepts into drawings that describe the full operation of the system and how further drawings, schedules, and diagrams are produced to enable the system to be constructed at the factories, installed, tested, and commissioned on site. Examples are given of a variety of different styles of presentation based on manufacturers and National Standards. The chapter concentrates on substation control and protection schemes, but the principles apply equally to most electrical plants. The starting point for new substation work is the block diagram or single line diagram (SLD). The advantage of this type of diagram is that the complete system can be seen as a whole in semipictorial form. Although not meant to be a detailed guide for the layout of the controls and instruments on the control panels, it is sufficiently concise to enable the designer to check that all the facilities required by the operator are present. Similarly for the relay cubicle, the block diagram only illustrates the general requirements for the siting of the relays. A single item on the block diagram could, for example, represent a complex relay scheme that in itself could occupy several racks on the protection panel.