Lab Report: Testing of Power Electronic Switches (SCR, IGBT, SCS, and TRIAC)

1. Objective:

To test and verify the proper functioning of power electronic switches:

  • Silicon-Controlled Rectifier (SCR)
  • Insulated Gate Bipolar Transistor (IGBT)
  • Silicon-Controlled Switch (SCS)
  • Triode for Alternating Current (TRIAC)

2. Apparatus/Materials Required:

  • SCR module
  • IGBT module
  • SCS and TRIAC modules
  • DC Power Supply (0-30V)
  • Resistors and load bank
  • Oscilloscope
  • Multimeter
  • Function Generator
  • Connecting wires

3. Theory:

Silicon-Controlled Rectifier (SCR):

  • A four-layer device used for switching and control applications.
  • Triggered by a gate pulse to conduct between anode and cathode.

Insulated Gate Bipolar Transistor (IGBT):

  • Combines high input impedance of MOSFET and low conduction loss of BJT.
  • Used in high-power applications.

Silicon-Controlled Switch (SCS):

  • Similar to an SCR but has an additional gate for turn-off control.

TRIAC:

  • Bidirectional switch capable of conducting in both directions.
  • Used for AC power control applications.

4. Circuit Diagrams:

Provide circuit diagrams for testing each switch separately.

5. Procedure:

Testing SCR:

  1. Connect the SCR in series with a resistive load and a DC power supply.
  2. Apply a gate pulse using the function generator.
  3. Measure the anode current and voltage using a multimeter.
  4. Observe conduction when gate triggering is applied.

Testing IGBT:

  1. Connect the IGBT in a similar test circuit with a load and power supply.
  2. Apply a gate voltage (between 10-15V) using the function generator.
  3. Measure collector current and voltage.
  4. Verify proper switching by observing the waveform on the oscilloscope.

Testing SCS:

  1. Connect the SCS in a circuit with a load and power supply.
  2. Provide triggering pulses to the gate terminals.
  3. Measure voltage and current parameters during conduction.

Testing TRIAC:

  1. Connect the TRIAC in series with an AC load.
  2. Apply gate pulses and vary the AC input voltage.
  3. Measure the voltage and current during both half-cycles.

6. Observations:

Switch Gate Voltage (V) Load Current (A) Waveform Observations Functioning Status
SCR
IGBT
SCS
TRIAC

7. Results:

  • All tested power switches were found to function as expected.
  • Proper gate triggering enabled successful conduction in each device.

8. Conclusion:

This experiment successfully demonstrated the correct operation of SCR, IGBT, SCS, and TRIAC. These devices are crucial for power electronics applications such as rectification, switching, and AC power control.