Exercise 1: Varying Resistive Load (without smoothing capacitor, C=0)

Open the Single-Phase Diode Bridge Rectifier panel, choose in the menu Pre-Selected: Single Phase: Varying Resistive Load without smoothing capacitor.

Figure 11: Single-Phase Diode Bridge Rectifier Panel with a Resistive Load of 16.5 ohms

Default Parameters

• AC Source Voltage : Ve= 120 V
• Frequency: 60 Hz
• R= 16.5 Ω

Keep the AC Source Voltage to 120 V, observe the waveforms, and calculate the average output current (load current) and fill out table 4 for different values of the resistance R.

Table 4: Effect of Varying Resistive Load

• Calculate the output frequency and compare it with the input frequency.
• Compare the input current with the output current and the input voltage with the output voltage.
• Deduce the role of the single-phase diode bridge rectifier.
• Justify the shape of the output voltage and output current.
• Calculate the form factor and the ripple factor.

Exercise 2: Varying Resistive Load (with smoothing capacitor)

In the panel, choose under Pre-Selected: Single Phase: Varying Resistive Load with smoothing capacitor.

Figure 12: Single-Phase Diode Bridge Rectifier Panel with R=16.5 ohms and C= 470 µF

Complete tables 5, 6, and 7 for different values of the smoothing capacitor.

Case 1: C= 470 µF

Table 5: Case 1- Varying Resistive Load With Smoothing Capacitor

Case 2: C= 1100 µF

Table 6: Case 2- Varying Resistive Load With Smoothing Capacitor

Case 3: C= 0.1 F

Table 7: Case 3- Varying Resistive Load With Smoothing Capacitor

Now, set R to 25 Ω.

• Compare the values of peak-to-peak output voltages (without and with smoothing capacitor).
• How does the ripple factor increase?
• What’s the relationship between the peak-to-peak output voltage and the resistance (when C is constant)?
• For which capacitor value is the filtering considered more effective?
• For which value of capacitor filtering is the minimum output voltage equal to 10% of the maximum peak value of the output voltage?
• What is the effect of increasing the capacitor filtering on the total harmonic distortion (THD) of the AC-source current?