SINUSOIDAL ALTERNATING QUANTITY

n alternating quantity (i.e., voltage or current) that varies according to sine of angle θ (θ = ωt) is known as ‘sinusoidal alternating quantity’. Its wave shape is shown in Figure 6.2(f). For the generation of electric power, sinusoidal voltages and currents are selected all over the world due to the following reasons:

1. The sinusoidal voltages and currents cause low iron and copper losses in AC rotating machines and transformers. This improves the efficiency of AC machines.
2. The sinusoidal voltages and currents offer less interference to nearby communication system (e.g., telephone lines)
3. They produce least disturbance in the electrical circuits.

Whenever the word ‘alternating voltage or current’ is used in this text, it means sinusoidal alternating voltage or current unless stated otherwise.

6.5  GENERATION OF ALTERNATING VOLTAGE AND CUR