Assignment Task
Introduction
This set of notes identifies equipment, safety concerns and methods of connection used for laboratory 2. Additional information is available in the lectures regarding calculation: lecture notes entitled “1- Phase Diode Full Bridge Rectifiers” and “3-Phase Full Bridge Uncontrolled Rectifiers” apply to this laboratory. Additionally the values of the capacitance available is not the same as specified in the lab manual C = 340µF. We apologise for this inconvenience to simulations.
Students are required to utilise the following three phase diode box for Lab 2. The following identifies how you can connect the diodes for single phase and three phase rectification. Note: it is important that you wait for the laboratory demonstrator to check your circuit before you switch anything on. If the leads are connected across the capacitor incorrectly this could result in damaging the capacitors. PLEASE ensure you check with the demonstrator first.
For this laboratory the capacitors available for the load are not the same as those specified in the lab manual, students are required to measure the capacitance during the lab session. Please ensure when you complete your simulations that you consider the correct values of capacitance, we apologise for any inconvenience. On connection of the capacitors seen in Fig. 4 we want to achieve a value closer to that specified in the lab manual. By connecting the capacitors in parallel the capacitance values add together as indicated by equation 1.
In addition ensure that the polarities of the leads connected to the capacitors are correct otherwise failure of the devices will occur. You may connect the positive lead to either of the positive terminals on the capacitance and same for the negative terminal as long as the positive is not connected to the negative and vice versa.
Part A – Experiment using single- and three-phase diode rectifier
Assemble the rectifier circuit as shown in Fig. 5. Use proper color in wiring e.g. white lead for ac source line, blue for neutral, red for positive dc and black for negative dc. The three phase ac voltage source is rated at 41.5-Volt 50Hz. Use line to neutral voltage to power the rectifier. Resistive load is 63 Ohm.
2. Connect voltage probes at Channel-1 & Channel-3 of DSO to obtain waveforms of Vs and Vo respectively.
3. Connect Tektronix current transducer to Channel-2, calibrate the transducer and measure the waveforms of Is and Io alternately.
4. Connect DMM to measure Vs(rms).
5. Have the circuit checked by an instructor prior to turning it on
6. Turn on the ac power supply switch.
7. Adjust your DSO until 2-5 cycles of Vs waveform is displayed on the screen. Save each pair of waveform (Vs & Vo), (Vs & Is) and (Vs & Io) using digital scope memory card. Find forward voltage drop across diode by observing Vs & Vo waveforms in detail.
8. Use DC coupling to obtain the average value of Io and AC coupling for Io_ripple(rms).
9. Complete the result sheet.
(b) Single phase (uncontrolled) rectifier with RC load
1. periment 1 (b) – Single phase (uncontrolled) rectifier with RC load 1. Assemble the rectifier circuit as shown in Fig. 6. Use proper color in wiring e.g. white lead for ac source line, blue for neutral, red for positive dc and black for negative dc. The three phase ac voltage source is rated at 41.5-Volt 50Hz. Use line to neutral voltage to power the rectifier. Resistive load is 63 Ohm. Capacitor is 540uF. Ensure capacitor polarity is correct.
2.Connect voltage probes at Channel-1 & Channel-3 of DSO to obtain waveforms of Vs and Vo respectively.
3. Connect Tektronix current transducer to Channel-2 to obtain waveforms of Is and Io lternately.
4. Connect DMM to measure Vs(rms).
5. Have the circuit checked by an instructor prior to turning it on.
6. Turn on the ac power supply switch.
7. Adjust your DSO until 2-5 cycles of Vs waveform is displayed on the screen. Save each pair of waveform (Vs & Vo), (Vs & Is) and (Vs & Io) using digital scope memory card.
8. Use DC coupling to obtain the average value of Io and AC coupling for Io_ripple(rms).
9. Complete the result shee
Experiment 2 Three phase (uncontrolled) rectifier with RL load
1. Assemble the rectifier circuit as shown in Fig. 7. Use proper color in wiring e.g. white lead for ac source line, blue for neutral, red for positive dc and black for negative dc. The three phase ac voltage source is rated at 41.5-Volt 50Hz. Resistive load is 63 Ohm. Inductor is 50mH.
2. Connect voltage probes at Channel-1 & Channel-3 of DSO to obtain phase voltage waveform of Vs and Vo respectively.
3. Connect Tektronix current transducer to Channel-2 to obtain waveforms of Is and Io alternately.
4. Connect DMM to measure Vs(rms).
5. Have the circuit checked by an instructor prior to turning it on.
6. Turn on the ac power supply switch.
7. Adjust your DSO until 2-3 cycles of Vs waveform is displayed on the screen. Save each pair of waveform (Vs & Vo), (Vs & Is) and (Vs & Io) using digital scope memory card.
8. Use DC coupling to obtain the average value of Io and AC coupling for Io_ripple(rms).
9. Complete the result sheet