5 Draw the voltage waveform across the TRIAC in the space provided making sure

# 5 draw the voltage waveform across the triac in the

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5. Draw the voltage waveform across the TRIAC in the space provided, making sure to align it with the proper degrees for one cycle (indicate peak-to-peak voltage). 6. Place the oscilloscope across R L . 7. Draw the voltage waveform across R L in the space provided, making sure to align it with proper degrees for one cycle. (Indicate peak-to-peak voltage) Figure 9.1 8. Modify the circuit as shown in figure 9.2 by adding the capacitor. 9. Place the oscilloscope across the TRIAC. 10.Vary R G back and forth and view the voltage waveform across the TRIAC. 11.Adjust R G so that the TRIAC triggers past 90 o and 270 o . 12.Draw the voltage waveform across the TRIAC in the space provided, making sure to align it with the proper degrees for one cycle (indicate peak-to-peak voltage). 13.Place the oscilloscope across R L . 14.Draw the voltage waveform across the R L in the space provided, making sure to align it with the proper degrees for one cycle (Indicate peak-to-peak voltage).
57 Figure 9.2
58 ________________________ AC TRIGGERING OF A TRIAC Experiment IX Group No._______ DOP:_______________ Section:___________ Time: _____________ Day ________Room______ Name:_______________________________ Signature_______________ Instructor:___________________________ DATA SHEET: GRAPH: Voltage waveform across the TRIAC using figure 9.1 Voltage waveform across the load resistor using figure 9.1
59 Voltage waveform across the TRIAC using figure 9.2 Voltage waveform across the load resistor using figure 9.2 FILL-IN QUESTIONS: 1. Using only a potentiometer, the ac trigger time of a TRIAC can be varied about to degrees and to degrees. 2. Using a potentiometer and a capacitor, the ac trigger time of a TRIAC can be varied over nearly one cycle.
60 3. When the TRIAC conducts, the voltage across R L is at out equal to the . 4. When the TRIAC conducts, the voltage across its main terminals is about V. 5. When the TRIAC is not conducting, the voltage across its main terminals is equal to the . ANALYSIS OF RESULTS:
61 QUESTIONS AND PROBLEMS: 1. Does the firing delay angle of a triac during the positive half cyclenecessarily equal the firing delay angle during the negative half cycle? 2. What happens to firing delay angle as temperature increases, assumingeverything else is constant? 3. Explain why the load power can be reduced by turning thepotentiometer backward once the triac has just barely started firing.
1. State how to set the PUT trigger voltage. 2. Demonstrate a practical go/no/go method of testing a PUT with an ohmmeter. 3. Demonstrate the turn on (firing) and turn off (reset) methods for a PUT. 4. Compare the PUT structure to that of the SCR. INTRODUCTION: The PN junction from anode to gate of a PUT can be tested with an ohmmeter similar to a regular diode. However, testing for cathode to gate will not indicate a working PUT because one of the PUT junctions with always be reversed biased. The PUT can be tested with an ohmmeter by placing the positive lead on the cathode with the gate will trigger the PUT, and the meter should indicate low resistance if the power source is sufficient to produce the necessary holding current.

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• Summer '17
• Alternating Current, Voltage divider, Resistor, power supply, Electrical resistance

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