What are the difference between linear & non- linear loads?

Question

Basically it is a part of electrical engineering and related to power distribution,which relates to harmonics

Answer 1

In a linear circuit, the output response is directly proportional to the input. In an AC circuit, that means that the application of a sunusoidal voltage results in a sinusoidal current. As the instantanious voltage changes over the period of the sine wave, the instantanious current rises and falls in proportion to the voltage so that the waveform of the current is also a sine wave.

If a circuit is composed of ideal resistors, inductors and capacitors, it is a linear circuit because those components are linear. Real components can have some non-linearity because of non-linear characteristics such as the saturation of a magnetic circuit. There are degrees of linearity. AC motors are nearly linear. A motor's load current is a sine wave with only a little distortion.

A rectifier circuit with a capacitor filter is very non-linear. The capacitor is selected so that it remain charged to nearly the peak value of the AC input voltage. When the load is applied, the capacitor dischrges to a slightly lower voltage during the time between one peak of the line voltage and the next. Current only flows through the diodes when the instantanious AC voltage exceeds the capacitor voltage. When the AC voltage approaches its peak, the voltage exceeds the capacitor voltage and the diode switches on allowing current to flow into the capacitor. As soon as the AC voltage passes its peak, the current stops. The input current to the rectifier is a series of short pulses rather than a sine wave. The current has a periodic waveform of the same frequency as the AC input voltage, but it is very distorted compared to a sine wave.