In this tutorial, I will explain you the working of RC and RL circuit. First the brief and concise introduction of capacitive and inductive circuits is provided explaining the effect of introducing each of them in a resistive circuit. After that the concept provided in introduction part is implemented with the help of PSPICE, and the theoretical results are compared with the virtual results of PSPICE which comes out to be same. At the end of the tutorial you are provided with an exercise to do it by yourself, and in the next tutorials I will assume that you have done those exercises and I will not explain the concept regarding them.
Introduction to RC and RL circuits
The very basic circuits in electrical engineering are RC and RL circuits, these circuits are analyzed only to test the behavior of capacitor and inductor on current and voltage. The introduction of a capacitor in a simple resistive circuits results in the voltage lead of 90 degrees from the current. Similarly, if we introduce an inductor in a simple resistive circuit, the output current will be leading the output voltage by 90 degrees. This leading and lagging of current and voltage in case of RC and RL circuits will be explained in this tutorial.
How to design RL and RC circuit in PSPICE
- Lets’ get started with the schematic portion of PSPICE. On the search bar of your computer type design manager a file saying “Pspice design manager” will pop up, as shown in the figure below,
Figure 1: Design manager
- With the installation of Pspice student version a number of files get installed on your PC. In the previous tutorial we used Capture student and now we are using pspice design manager. Both of them are same you can use any of them according to your choice.
- After you open the design manager a window will appear as shown in the figure below,
Figure :2 Design manager window
- This is the design manager window you have to open the schematic window first to draw the circuit you want to implement. Click on the run schematic option on the left bar of this window to open a schematic window where you will place your design as shown in the figure below,
Figure 3: Run schematic button
- The schematic window in which you will design you circuit is shown in the figure below,
Figure 4: PSPICE schematic window
- First of all, save this schematic before jumping into drawing part, so that the circuit may not be lost and we can access it in future anytime. Click on the file at the top left corner of the schematic widow and then click on save as shown in the figure below,
Figure 5: Saving schematic
- On the top bar of the schematic window there is a button named get new part, this button is used to place a new electronic part in the circuit as shown in the figure below,
Figure 6 : Get new part.
- Clicking on this button will open a window from which we will select the part of the circuit in future, as shown in the figure below,
Figure 7 : Get new part window
- On the part name block on this window type the name of the part you want to place on you circuit diagram. For instance, I want to place a resistor, a capacitor, an AC power supply and a ground to earth in this example, so I will first type R in the part name block which will allow me to select the resistor from the list and then click on place & close option as shown in the figure below,
Figure 8: Placing resistor
- Again open the get new part window and in the pat name block type capacitor or just capacitor, select the C from the list given and then click on place & close as shown in the figure below,
Figure 9: Placing capacitor
- Place the component in the circuit diagram, and again open the get new part window and in the pat name block type Vsin, select the supply from the list given and then click on place & close as shown in the figure below
Figure 10: Placing Vsin
- Next step is to place a ground, do the same again and in the part name type Gnd and select the ground and then click on place & close as shown in the figure below,
Figure 11: Placing ground
- The placed components in the schematic window are shown in the figure below,
Figure 12: Placed components
- Next step is to make connections between all these components, on the top bar of the schematic window, select place wire option as shown in the figure below,
Figure 13: Placing wire
- Connect all the components with the wire. Now set the properties of the Vsin block, i.e. double click on the Vsin component and the properties window will appear as shown in the figure below,
Figure 14: Properties window
- Change the values of VAMPL, VOFF and FREQ according to your need and click on Save Attr after updating each value, as shown in the figure below,
Figure 15: Saved attributes
- On the top of the schematic window, click on the Voltage/Level Marker button and place it at the node between capacitor and resistor as shown in the figure below,
Figure 16: Complete circuit diagram
- Next step is to adjust the properties of the simulations in order to produce the graph of the voltage at the marker. Click on analysis and then click on Setup as shown in the figure below,
Figure 17: Setting up analysis
- A widow will appear, click on the transient block on the window and adjust the properties of the window according to your requirement, refer to the figure below
Figure 18: Transient properties
- Now comes the simulation part, click on the analysis at the top bar of the schematic window and then click on simulate as shown in the figure below,
Figure 19: Simulation window
- A schematic window will appear showing the voltage across the capacitor as shown in the figure below,
Figure 20: Simulation window
- But how to verify that the circuit is working properly. For that purpose, click on the plot at the top bar of the window, and then select Add Y axis because the magnitude of current and voltage are highly different. Refer to the figure below,
Figure 21: Add y axis
- Click on the trace (next to plot) and then click on add trace as shown in the figure below,
Figure 22: Adding trace
- A window will appear asking you which trace you want to see. Click on the current of the capacitor and then click ok as shown in the figure below,
Figure 23: Capacitive current
- The plot of the capacitive current along with the capacitive voltage will appear on the second plot you created by adding y axis. Refer to the figure below, showing both the voltage and current on a single graph.
Figure 24: Output voltage and current
- It is obvious from the figure that the current is lagging the voltage, hence the circuit is working properly.
Exercise:
⦁ Try to work with RL circuit. Use the similar fashion as discussed here except using inductor in place of capacitor.
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