ABSTRACT
This chapter helps readers to sketch a balanced, three-phase, delta-connected load, showing all voltage and current 'sense arrows' and construct a three-phase phasor diagram for a balanced star- and delta-connected load, showing all line and phase voltages and currents. Three-phase line conductors and terminals are identified in various ways, according to relevant national electrical standards. The chapter explains the major advantages of three-phase alternating current systems, compared with single-phase alternating current systems and describes delta- and star-connected systems. Almost without exception, alternating current is generated, transmitted and largely distributed using three-phase systems which use three conductors rather than the two required by single-phase systems. The main reason for this is economy, because it can be shown that, for a given load, and despite the additional conductor, the overall volume of copper required by a three-phase system is approximately 75 per cent of that required by an equivalent single-phase system.
