Category: 6. AC Fundamentals

Consider a coil having ‘N’ turns rotating in a uniform magnetic field of density B Wb/m2 in the counterclockwise direction at an angular velocity of ω radians per second as shown in Figure 6.6. At the instant, as shown in Figure 6.6(b), maximum flux ɸm is linking with the coil. After t seconds, the coil is rotated through an angle θ = ω t radians. The component of flux…

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: Whenever the word ‘alternating voltage or…

AC DC (1) An alternating current reverses periodically and its magnitude changes. (1) Direct current flows only in one direction and remains unaltered. (2) Amplitude and polarities are varying continuously.  (2) Amplitude and polarities are fixed. (3) It has a particular frequency. (3) It is independent of frequency. (4) AC can be generated at higher…

A voltage that changes its polarity and magnitude at regular intervals of time is called an ‘alternating voltage’. When an alternating voltage source is connected across a load resistor R as shown in Figure 6.1, the current flows through it in one direction and then in opposite direction when the polarity is reversed. Figure 6.1(c) shows the…

As discussed earlier, the flow of current in the circuits was steady and in only one direction, that is, direct current (DC). The use of DC is limited to few applications, for example electroplating, charging of batteries, electric traction, electronic circuits, etc. However, for large-scale power generation, transmission, distribution, and utilization, an alternative current (AC)…