2. Switch on the 230V AC supply through three-pin power chord. 3. Keep the gate current (I G ) to a suitable value (say minimum of 4 mA to 5mA) 4. Now slowly increase the anode-cathode voltage (V AK ) by varying the pot till Triac get turned on, with the indication that anode cathode voltage decreases to it's on state voltage drop (i.e 0.7V) and the anode current increases. 5. Note the values of voltmeter (V AK ) which is the break over voltage and the ammeter (I L ) which is the latching current value. 6. Further, increase the anode current in steps by varying the anode-cathode voltage and note the readings. 7. Now reduces the anode cathode voltage (V AK ) till the triac turned off and find the holding current. 8. For various gate current take the readings and tabulate it. 9. Connect MT 2 terminal of Triac is + Ve with respect to MT 1 10. Repeat the same procedure from 2 to 8 11. Finally, a graph of anode current V s anode-cathode voltage is plotted for various gate current for forward and reverse biases. Single-phase A.C phase controller for illumination control 1. Connections are made as per the circuit diagram. 2. Switch on the 230 V, 50 Hz AC supply 3. By varying potentiometer, vary the firing angle of the converter in order to vary the output voltage there by the illumination of the lamp will be varied. 4. For each step note down the firing angle, ammeter reading, voltmeter reading and the output voltage waveform from and tabulate it. 5. Finally, the output voltage waveform is plotted and the theoretical RMS voltage is calculated. Daffodil International University 14
Power Electronics Lab Manual TABULATION: VI Characteristics: MT 1 is + Ve with respect to MT 2 S.No. 1 2 3 4 5 V AK (V) I G1 = I A (mA) V AK (V) I G2 = I A (mA) V AK (V) I G3 = I A (mA) MT 2 is + Ve with respect to MT 1 I G1 = I G2 = I G3 = S.No. 1 2 3 4 5 V AK (V) I A (mA) V AK (V) I A (mA) V AK (V) I A (mA) Single-phase A.C phase controller S.No. Firing angle ( ) in I 0RMS Measured V 0RMS Measured V 0RMS Calculated degree in Amps in Volts in Volts 1 2345 Daffodil International University 15
Power Electronics Lab Manual INFERENCE: DISCUSSION QUESTIONS: 1. What is bidirectional device? 2. What is bipolar device? 3. What are the applications of phase controlled converter in home appliances? 4. What is the number and range of given triac? 5. What type of firing is used here?
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- Fall '13
- Alternating Current, Rectifier, AC power, DAFFODIL INTERNATIONAL UNIVERSITY, Power Electronics Lab