ABSTRACT

This chapter explains the difference and the similarity between single-phase and three-phase systems, and the advantages of three-phase systems. It shows why three-phase systems are more common in industry, and the relationships in single-phase AC electricity to three-phase systems. The chapter explores delta and wye connections in three-phase electricity and describes the relationships and differences between wye and delta connections. It provides a distinction between balanced and unbalanced loads, power and power factor in three-phase electricity, and power factor correction for three-phase electricity. A three-phase load is a set of three exactly similar combinations of electric components arranged in exactly the same way. Current flows from the source to the loads and while the instantaneous direction and magnitudes of the currents in the three lines are not the same, their effective magnitudes are equal, because the loads are assumed to be similar.