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510 ⏐⏐⏐ INDUCTORS
Electronics Workbench
The transient response of an R-L network can also be obtained using
Electronics Workbench. The circuit to be examined appears in Fig.
12.63 with a pulse voltage source to simulate the closing of a switch at
t � 0 s. The source, referred to as PULSE – VOLTAGE – SOURCE in
the Source listing, is the near the bottom left of the Sources parts bin.
When selected, it will appear with a label, an initial voltage, a step voltage,
and a frequency. All can be changed by simply double-clicking on
the source symbol to obtain the Pulse Voltage dialog box. As shown in
Fig. 12.63, the Pulsed Value will be set at 20 V, and the Delay Time to
0 s. The Rise Time and Fall Time will both remain at the default levels
of 1 ns. For our analysis we want a Pulse Width that is at least
twice the 5t transient period of the circuit. For the chosen values of R
and L, t � L/R � 10 mH/100 � � 0.1 ms � 100 ms. The transient
period of 5t is therefore 500 ms or 0.5 ms. Thus, a Pulse Width of 1 ms
would seem appropriate with a Period of 2 ms. The result is a frequency
of f � 1/T � 1/2 ms � 500 Hz. When all have been set and
selected, the parameters of the pulse source will appear as shown in Fig.
12.63. Next the resistor, inductor, and ground are placed on the screen
to complete the circuit.
This time we will want to see the node names so that we can call for
them when we set up the simulation process. This is accomplished
through Options-Preferences-Show node names. In this case we have
two—one at the positive terminal of the supply (1) and the other at the
top end of the inductor (2) representing the voltage across the inductor.
The simulation process is initiated by the following sequence: Simulate-Analyses-Transient
Analysis. The result is the Transient Analysis
dialog box in which Analysis Parameters is chosen first. Under
FIG. 12.63
Using Electronics Workbench to obtain the transient response for an inductive circuit.