ABSTRACT
Single-phase circuits are frequently used in low power applications such as lighting, heating, single-phase motors and a few large electric motors in residential and small or medium sized industries. The single-phase circuits can be used as part of three-phase circuits or as an independent single-phase system. Most single-phase applications assume voltage and current waveform as sinusoidal. When these waveforms are not sinusoidal, the errors may occur in measurements of electrical quantities and this may also lead to the maloperation of electrical equipment. Under these conditions, it is necessary to evaluate the measuring techniques used in power systems with the increased power electronic based loads and other non-linear loads. Therefore, the definitions of power and its various components are very important to understand the quantitative and qualitative power quality aspects in power systems and are discussed in this chapter. Various power terms and components such as instantaneous power, instantaneous active and reactive powers, and real and reactive powers under sinusoidal and non-sinusoidal voltage and currents are derived from the first principles and explained. For each conceptual discussion, illustrative examples are presented. Some problems are given at the end of the chapter, which will enable the reader to develop insight and skills to understand and solve the issues related to power quality in single-phase systems.
