5.11 : Parallel RLC Circuits

Street lamps equipped with RLC surge protectors are an excellent example of applying circuit analysis in practical scenarios. These surge protectors safeguard the lamp's components against sudden voltage spikes.

A simplified parallel RLC circuit model with a DC input source generating a step response is employed in this context. When the switch is turned on, Kirchhoff's current law is applied, leading to a second-order differential equation.

Interestingly, this equation's solution comprises both transient and steady-state responses. The transient response gradually diminishes over time, exhibiting similarities to the source-free series RLC circuit solutions under different damping conditions. If the damping factor surpasses the resonant frequency, the response becomes overdamped.

When these two factors match, the response is critically damped.

The response turns underdamped if the damping factor is less than the resonant frequency.

The steady-state response corresponds to the final inductor current, aligning with the source current. Determining the constants involved relies on the initial conditions of the circuit.

Notably, only the transient response remains when the input source current is eliminated. Parallel RLC circuits find extensive applications, particularly in communications networks and filter designs. Understanding their behavior under different damping scenarios contributes to adequate surge protection and circuit design in practical settings.