Wentworth Institute of Technology Name:
Department of Electronics and Mechanical Date:
ELEC 195 - Circuits Theory II
Experiment 4
The Step and Natural Response of an RL Circuit
Objective:
1. To become familiar with the step response of an RL circuit.
2. To become familiar with the natural response of an RL circuit
Equipment Required:
PC with Pspice
Resume of Theory:
The response of a circuit to the sudden application of a constant voltage or current
source is referred to as the step response of the circuit (shown in Fig. 3.1 when the
switch is thrown to position B). In an RL circuit the initial conditions to determine the step
response are assumed to Io. The expressions for the current in the circuit and the voltage
across the inductor after the voltage source is applied are:
)1()(
/
t
e
R
Vs
ti
/
*)(
t
eVstV
The expression for the inductor current indicates that the current increases from zero to a
final value of Vs/R at a rate determined by the time constant = L/R
Fig. 3.1
A. Khabari Wentworth Inst. of Tech.
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