DC Transients and AC transients

            In general, if the network has a resistor then at the time of switching there won't be any transients. The transient occurs in the network due to the energy-storing elements.

The energy stored in the inductor and capacitor cannot change instantaneously and this behavior on the inductor and capacitor leads to the transients in the network.

The transients are of two kinds based on the voltage and current continual change in the circuit.

• DC Transients
• AC Transients

The network is said to be in a steady-state whenever the energy stored in the network is maximum and constant.

Energy stored in an inductor, 

when iL = maximum and constant

The inductor short circuits in a steady state. In steady-state conditions, the inductor acts as a constant current source.

Energy stored in the capacitor, 

 

when Vc = maximum and constant

The capacitor opens in a steady state. In steady-state conditions, the capacitor acts as a constant voltage source.

Proof for inductor current after switching is equal to the inductor current before switching.

Transient behavior of Inductor:

The inductor current at t=0+ and t=0-

For all excitations except impulse,

The inductor current can change instantaneously for impulse voltage across it,

Transient behavior of Capacitor:

The capacitor voltage cannot change instantaneously.

For all excitations except impulse,

The voltage across the capacitor cannot change instantaneously except impulse as follows.

Current free inductor: