In Figure 3.2a, we see a circuit with a line supplying an electric motor.
Note that the line impedances cause a voltage drop when currents are
drawn from the line. When the motor is energized, the motor current
Im causes a voltage drop to other loads in the system at the point of
common coupling (PCC). Figure 3.2b displays a voltage sag due to a large
motor starting, such as a pump or air-conditioner motor. Note that when
an induction motor starts, it can draw very high currents until the rotor