Global Specialties Global Specialties PB-600 Manual

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Power Electronics Course

Introduction to the Fundamentals of Power Electronics

PB-600

Student Lab

Manual

Power Electronics Course

Student Lab Manual

PB-600

Global Specialties

22820 Savi Ranch Parkway

Yorba Linda, CA 92887

www.globalspecialties.com

All Rights Reserved. No part of this book shall be reproduced, stored in a retrieval system, or transmitted by any means, electronic, mechanical, photocopying, recording, or otherwise, without written permission from the publisher. No patent liability is assumed with respect to the use of information contained herein. While every precaution has been taken in the preparation of this book, the publisher assumes no responsibility for errors or omissions. Neither is any liability assumed for damages resulting from the use of the information contained herein.

451-069-001_rA

Power Electronics Student Lab Manual

Table of Contents

Introduction 7

Technical Specications 7

Panel Layout 8

About the Trainer 9

Operating Instructions 10

Answers (Pre-Lab) 80

List of Included Accessories 84

Power Electronics Student Lab Manual

Experiments

Experiment 1: Characteristics of an SCR 11

Experiment 2: Gate Control Characteristics of an SCR 13

Experiment 3: The UJT, Inter Base Resistance, and Intrinsic Standoff Ratio 15

Experiment 4: Characteristics of a MOSFET 17

Experiment 5: Characteristics of an IGBT 19

Experiment 6: Characteristics of a DIAC 21

Experiment 7: The IA - VA Characteristics of a TRIAC 23

Experiment 8: Characteristics of a PUT 26

Experiment 9: Class B Commutation Circuit 28

Experiment 10: Class C Commutation Circuit 30

Experiment 11: Class D Commutation Circuit 32

Experiment 12: Class F Commutation Circuit 34

Experiment 13: Resistor Triggering Circuit 36

Experiment 14: Resistor Capacitor Triggering Circuit (Half Wave) 38

Experiment 15: Resistor Capacitor Triggering Circuit (Full Wave) 40

Experiment 16: Triggering an SCR with a UJT 42

Experiment 17: Triggering an SCR with a IC-555 44

Experiment 18: Triggering an SCR with a IC-741 46

Experiment 19: RAMP and Pedestal Triggering Using Anti parallel SCR 48

Experiment 20: UJT Relaxation Oscillator 51

Experiment 21: Voltage Commutated Chopper 53

Experiment 22: Bedford Inverter 55

Experiment 23: Single Phase PWM Inverter with MOSFET 57

Experiment 24: Single Phase PWM Inverter with IGBT 59

Experiment 25: Half Wave Controlled Rectier with Resistive Load 61

Experiment 26: Half Wave Controlled Rectier with RL Load 63

Experiment 27: Full-Wave Controlled Rectier (Mid Point Conguration) with Resistive Load 65

Experiment 28: Full-Wave Controlled Rectier (Mid Point Conguration) with RL Load 68

Experiment 29: Fully Controlled Bridge Rectier with Resistive Load 70

Experiment 30: Fully Controlled Bridge Rectier with RL Load 72

Experiment 31: Low Side Buck Converter with Resistive Load 74

Experiment 32: Boost Converter with Resistive Load 76

Experiment 33: Buck-Boost Converter with Resistive Load 78

Power Electronics Student Lab Manual

Introduction

The PB-600 provides a complete workstation for students to experiment with Power Electronics Circuits. Each exercise, presented in the lab manual, guides the students with step-by-step procedures. These experiments can be performed in the electronics laboratory of Colleges and Universities. It may also be utilized in Technical Training centers as well. The intention is to better acquaint students with the characteristics of Power Electronics

devices and their applications. The Power Electronics Trainer will be benecial to Students majoring in

Engineering / Technology.

Technical Specications

1280 tie points and 4 Bus Strips with 100 tie points

Breadboard

DC Power Supply

AC Power Supply

Triggering Circuit

Single Phase Rectier

Pulse Amplier

SCR Assembly

Power Devices

Circuit Components

Potentiometer

Load Resistance

Pulse Transformer

Toggle Switch

Power Requirements

each, totaling 1680 tie points. Size 112mm x 170mm (Approx.)

± 5V at 100mA, ± 12V at 150mA, ± 15V at 50mA & ± 35V at 50mA

18V - 0V - 18V at 50mA, & 15V - 0V - 15V at 50mA

5 gate signal output, Frequency range: 40Hz to 900Hz Variable, Amplitude: 12V PWM control of G1, G2, G3 and G4 Duty cycle control of “Gate” Signal is 0 to 100%

Firing Angle Control 0°-180° variables

Firing Circuit Four gate signal output with isolation transformer

2P4M (4 pieces) 600V, 2A

IGBT-G4BC20S;MOSFET-IRF540; UJT-2N2646, DIAC-DB3; TRIAC-BT136; PUT- 2N6027; SCRTYN-612/02

Capacitor: 0.01uF, 0.047uF, 0.1uF, 0.33uF, 1uF/63V (4 pieces), 2.2uF/50V

Diode: IN4007 (8 pieces), Zener Diode 9V, Inductor: 10mH, 68mH (2 pieces)

Resistor: 22Ω/5W, 100Ω/2W, 220Ω/2W, 10KΩ (3 pieces), 22KΩ, 33KΩ, 47KΩ,

4.7KΩ (2 pieces), 1MΩ,

120Ω, 270Ω, 1KΩ, 2.2KΩ, (Each 5W)

1:1 (2 pieces), 1:1:1

SPDT

115V ±6% 60Hz or 230V ±10%, 50Hz

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Panel Layout

Power Electronics Student Lab Manual

About the Trainer

Block 01: DC Power Supply

Fixed DC output of +5V and -5V, +12V and -12V, +15V and -15V, +35V and -35V

Block 02: AC Power Supply

Fixed AC output of 18V-0V-18V and 15V-0V-15V

Block 03: Circuit Component

Diodes: IN4007 (8 pieces), Zener Diode 9V, Capacitors: Cap 0.01 µF, Cap 0.047 µF, Cap 0.33 µF, Electrolytic Cap 1µF / 63V (4 pieces), 2.2µF / 63V

Resistors: 22Ω/5W, 100Ω/2W, 220Ω/2W, 10KΩ 0.25W (3 pieces), 22KΩ 0.25W, 33KΩ 0.25W, 47KΩ 0.25W

Inductors: 68mH (2 pieces), 10mH

Block 04: Power Devices

SCR TYN-612 (2 pieces), MOSFET IRF-540, IGBT- G4BC2OS, UJT 2N2646, PUT 2N 6027, DIAC DB-3, and TRIAC BT-136

Block 5: Toggle Switch

Single Pole Double Throw (SPDT)

Block 6: Pulse Amplier & Isolation Transformer

This block provides amplication of gate signal, and it isolates the power circuit from the triggering circuit.

Block 7: Breadboard

840 X 2 Breadboard

Block 8: Triggering Circuit

(4) Gate Pulse with PWM Control and Frequency Control. (1) “GATE” signal with Duty Cycle Control Block 9: Load Selector, Resistive Load

Loads: 120 Ω /5W, 270 Ω /5W, 1K Ω /5W, 2.2K Ω /5W: with Load Selector

Block 10: Potentiometer

1MΩ and 4.7KΩ (2)

Block 11: SCR Assembly

SCR 2P4M Assembly (4 pieces)

Block 12: Single Phase Controlled Rectier Firing Circuit

(4) Gate and Cathode signal with isolation for single phase-controlled rectiers.

Block 13: Pulse Transformers:

Pulse Transformers for circuit isolation: (2) Transformers of 1:1 and (1) Transformer of 1:1:1.

WARNING:

Because of the potential hazard of working with electrical circuits, all proper precautionary measures should be

taken when operating this unit. Failure to do so could result in injury.

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Power Electronics Student Lab Manual

Operating Instructions

The trainer contains an AC and DC power supply, with various voltages. The power supply is controlled by the ON/OFF switch. When turned on, the LED on the ON/OFF switch will light up, indicating the power supply has been activated.

The ‘TRIGGERING CIRCUIT” block, contains a Frequency, PWM, and Duty Cycle control. The “FREQUENCY” control will vary the frequency of pulse signals G1, G2, G3, G4 and GATE. The “PWM CONTROL” will vary the pulse width for inverter circuits. The “DUTY CYCLE” control will vary duty cycle of “GATE” only.

In the “SINGLE PHASE CONTROLLED RECTIFIER FIRING CIRCUIT” block, the gate signals for two groups of

rectier devices. The ring angle is changed by rotating “FIRING ANGLE CONTROL POT”.

The “PULSE AMPLIFIER & ISOLATION TRANSFORMER” block can be used for Bedford inverter and series inverter circuits.

The experiments presented in this manual are for guidance only. The trainees are expected to apply their knowledge and skills to modify or correct any circuits wherever necessary. Pin diagrams, for the devices, are provided at the end of the manual. Use them for proper connections.

Power Electronics Student Lab Manual

Experiment 1:

Characteristics of an SCR

Introduction:

The Silicon-Controlled Rectier (SCR) is a common and crucial component in Power Electronics circuits. Like a

diode, the SCR has both an anode and cathode aspect to it. However, what distinguishes an SCR from a typical diode is that it contains a gate input. The SCR will conduct in forward conduction mode if a high enough voltage is applied across the anode and cathode. Forward conduction may also be achieved by applying a positive signal to the gate. This lab will cover the voltage characteristics of an SCR and the forward conduction mode.

Pre-Lab Questions:

1. What is the main difference between an SCR and a typical Diode?

2. What is the P-N Conguration of an SCR, and where, in this P-N structure, is the Cathode, Anode, and

Gate connected?

3. A process referred to as doping is usually employed to control the number of charge carriers in a

semiconductor. What is this doping process, and why is it important in a P-N junction?

Apparatus Required: Quantity:

Resistance 510Ω, ¼ W 1

Resistance 2.2KΩ, 5W (on board) 1

SCR TYN 612 (on board) 1

Potentiometer 4.7KΩ (on board) 2

Multimeter 3

Patch Cord 10

Circuit Diagram:

The circuit below can be used to plot the characteristics of an SCR.

Figure 1

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Power Electronics Student Lab Manual

Gate Current IG = __________mA

Vol tage V

and Current I

(mA)

No.

Procedure:

1. Connect the circuit as shown in Figure 1 using patch cords.

2. To plot the IA - VA characteristics proceed as follows.

3. Rotate potentiometer P1 and P2 in the full counterclockwise position. Connect the voltmeter at point ‘6’ & ground to measure VG and at point ‘3’ & ground to measure VA.

4. Connect an ammeter between points ‘1’ & ‘2’ to measure the current IA and between points ‘4’ & ‘5’ to measure the gate current IG.

5. Switch Power ON.

6. Set the gate current IG to a value between 3.75mA - 3.85mA, by varying potentiometer P2.

7. Gradually increase anode voltage VA, by varying potentiometer P1.

8. Observe current IA, it should read near zero initially.

9. At some point, the positive anode current IA will have a sudden jump in reading. When this occurs, the

voltmeter reading will drop to near zero. This will indicate the ring of the SCR.

10. If this does not occur, repeat steps 5 - 8 with a slightly higher gate current IG value set.

11. As VA is being increased, record the observed voltage VA and corresponding current IA values on the table provided.

12. After the ring of the SCR, continue to increase VA, and record the observed VA and corresponding IA values.

13. Use the recorded values to plot and graph the IA vs VA curve.

Table 1: SCR Measured Values:

Image 1: SCR I vs V Curve

Power Electronics Student Lab Manual

Experiment 2:

Gate Control Characteristics of an SCR

Introduction:

An SCR is like a diode, but the SCR has an added gate control to it. Sending a pulse through the gate of the SCR will enable it to enter forward conduction mode. While the gate remains positive the SCR can conduct current in the forward conduction mode. This lab covers how an SCR turns on and off by controlling the gate input.

Pre-Lab Questions:

1. What are two methods that will generate forward conduction in an SCR?

2. What is Breakover Voltage in an SCR?

3. What is the holding current in an SCR?

Apparatus Required: Quantity

Resistance 510Ω, ¼ W 1

Resistance 2.2KΩ, 5W (on board) 1

SCR TYN 612 (on board) 1

Potentiometer 4.7KΩ (on board) 2

Multimeter 4

Patch Cord 16

Circuit Diagram:

The circuit below can be used to plot the characteristics of an SCR.

Figure 2

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Power Electronics Student Lab Manual

No.

Vol tage V

and Gate Current I

(mA)

Procedure:

1. Connect the circuit as shown in Figure 2 using patch cords.

2. To plot the IG - VA characteristics proceed as follows.

3. Rotate potentiometer P1 and P2 in the full counterclockwise position. Connect voltmeter at point ‘6’ & ground to measure VG and at point ‘3’ & ground to measure VA.

4. Connect ammeter between points ‘1’ & ‘2’ to measure the current IA and between points ‘4’ & ‘5’ to measure the gate current IG.

5. Switch Power ON.

6. Set voltage VA to 5V by varying potentiometer P1.

7. Gradually increase the gate current IG until the SCR is triggered. A sudden increase in the measured IA and

a drop, to a near zero reading, in the measured VA, is an indication that the SCR has red on.

8. On the table provided, record the measured current IG value at which the SCR is triggered.

9. After the ring of the SCR, continue to increase the gate current IG and observe whether it has any effect on IA or VA.

10. Increase VA by increments of 5V and repeat steps 5 – 8. Continue this process until a minimum of ve points, to plot, have been acquired.

11. Plot and graph the IG vs VA curve.

Table 2: SCR Measured Values

Power Electronics Student Lab Manual

Experiment 3:

The UJT, Inter Base Resistance, and Intrinsic Standoff

Ratio

Introduction:

A unijunction transistor (UJT) is a unique three terminal semiconductor device. When the UJT is triggered, the

emitter current increases until limited by the emitter power supply. It can be used in switching pulse generators,

and as a triggering device for an SCR or TRIAC. This lab will cover the characteristics of the UJT to nd the inter

base resistance as well as the intrinsic standoff ratio. This is done by observing the change in emitter current. Pre-Lab Questions: What is the UJT physical structure with respect to P-type and N-type material? In what way will applying positive voltage to the emitter affect the total resistance between base 1 and base 2? What is the inter-base resistance and the intrinsic stand-off ratio?

Apparatus Required: Quantity

Resistance 510 Ω ¼ W 2

Potentiometer 4.7K (on board) 2

UJT 2N2646 (on board) 1

Multimeter 3

Patch Cord 9

Circuit Diagram:

The circuit below can be used to plot the characteristics of a Unijunction Transistor.

Figure 3

Procedure:

1. Connect the circuit as shown in Figure 3 using patch cords.

2. To plot the Emitter characteristics, proceed as follows:

3. Rotate potentiometer P1 and P2 in the full counterclockwise position.

4. Connect the voltmeter at point ‘6’ and ground to read VBB and at point ‘3’ and ground to read VE.

5. Connect ammeter between points ‘1’ and ‘2’ to measure the emitter current IE, and between points ‘4’ and ‘5’ to measure the base current IB.

6. Switch Power ON.

7. Vary potentiometer P2 and set a voltage value of VBB = 5V.

8. Increase the Emitter voltage VE in steps.

9. Continue to increase VE until the reading on the voltmeter drops. At this point the UJT res on and emitter

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Power Electronics Student Lab Manual

123

789

No.

= 10V

= 15V

Emitter Voltage V

and Emitter Current IE (mA)

= 5V

current will ow rapidly.

10. In Table 3, record the Emitter voltage VE and the corresponding Emitter current IE for each observation value.

11. Repeat steps 4 through 8 for VBB = 10V and VBB = 15V.

12. Plot the VE vs IE graph with the observation values recorded on table 3.

Table 3: UJT Measured Values

Image 3: UJT V vs I Curve

Calculations:

Inter base Resistance (RBB)It is the sum of resistance between base 1 & base 2 RBB = RB1 + RB2

It ranges from 4K to 10K ohms when IE = 0.

Intrinsic stand-off Ratio (η) η = R B1 / (R B1+R B2) = RB B1 / RBB

It ranges from 0.51 to 0.82.

Power Electronics Student Lab Manual

Experiment 4:

Characteristics of a MOSFET

Introduction:

The Metal Oxide Semiconductor Field Effect Transistor (MOSFET) is a device used in a variety of different circuits. Because of its small compact size, it is used as a switch in analog and digital circuits. It is a four terminal device consisting of a source, gate, drain and base terminal. The base and source are usually connected, so the MOSFET operates as a three-terminal transistor. This lab will cover the characteristics of a MOSFET device with a focus on the voltage and current plots.

Pre-Lab Questions:

MOSFET is an acronym for Metal Oxide Semiconductor Field Effect Transistor. Why is it considered a eld effect

transistor? What makes it different from an SCR or UJT? According to the MOSFET circuit symbol printed on the face of the Trainer, Is this MOSFET an N-channel or P-channel? What is the P-N structure of the MOSFET, used in this lab?

Apparatus Required: Quantity

Resistance 820Ω, ¼ W 1

Resistance 1KΩ, 5W (on board) 1

Resistance 510Ω, ¼ W 1

Zener diode 9V (on board) 1

Potentiometer 4.7KΩ (on board) 2

MOSFET IRF540N (on board) 1

Multimeter 3

Patch Cord 14

Circuit Diagram:

The circuit below can be used to plot the characteristics of a MOSFET

Figure 4

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Power Electronics Student Lab Manual

No.

= _______

Vol tage V

and Current ID (mA)

= _______

1012

Procedure:

1. Connect the circuit as shown in Figure 4 using patch cords.

2. To plot the ID vs VDS characteristics, proceed as follows:

3. Connect the circuit using the breadboard

4. Rotate potentiometer P1 and P2 in the full counterclockwise position.

5. Connect an ammeter between points ‘1’ and ‘2’ and connect a second ammeter between points ‘4’ and ‘5’.

6. Connect a voltmeter at point ‘6’ and ground to measure drain voltage VDS. Connect voltmeter at point ‘3’ and ground to measure gate voltage VGS.

7. Switch Power ON

8. Vary potentiometer P1 and set the gate voltage VGS at some constant value (2.5V, 2.6V, 2.7V)

9. Increase the drain voltage VDS value from 0 to 35V in steps by varying potentiometer P2. In Table 4, record the measured Drain voltage VDS and corresponding Drain current ID values, with the constant Gate voltage VGS set.

10. Rotate potentiometer P2 in the full counterclockwise position.

11. Repeat steps 1 through 6 with a different gate voltage VGS value set.

12. Plot and graph the ID vs VDS curve using the recorded measured values, appropriately scaled. The graph will produce the Drain characteristics curve for a MOSFET.

Table 4: Observations

Image 4: MOSFET I vs V Curve

Power Electronics Student Lab Manual

Experiment 5:

Characteristics of an IGBT

Introduction:

The Insulated Gate Bipolar Transistor (IGBT) is a three terminal semiconductor device. Like a MOSFET, it can

operate as a switch due to its high efciency and fast switching capabilities. The IGBT is used in many high-

power applications such as electric cars, variable frequency drives and refrigerator units. This lab will cover the characteristics of an IGBT device, with a focus on voltage and current plots.

Pre-Lab Questions:

How will increasing the gate current affect the current ow through the IGBT?

According to the provided Data Sheet, what is the maximum voltage VCES that should be applied across the IGBT, being used in this experiment?

Apparatus Required: Quantity

Resistance 22Ω, 5W (on board) 1

Resistance 1KΩ, ¼ W 1

Potentiometer 4.7KΩ (on board) 2

IGBT G4BC20S (on board) 1

Multimeter 3

Patch Cord 11

Circuit Diagram:

The circuit below can be used to plot the characteristics of an IGBT.

Figure 5

Procedure:

1. Connect the circuit as shown in Figure 5 using patch cords.

2. Rotate the potentiometer P1 in the full clockwise position and P2 in the full counterclockwise position.

3. Connect the rst ammeter between points ‘4’ and ‘5’ to measure Collector current IC (mA).

4. Connect the second ammeter between points ‘1’ and ‘2’.

5. Connect voltmeter at point ‘3’ and ground to measure the Gate voltage VGE and at point ‘6’ and ground to

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Power Electronics Student Lab Manual

No.

= _______

Vol tage V

and Current IC (mA)

measure Collector voltage VCE.

6. Switch Power ON.

7. Vary the potentiometer P1 to set the gate voltage VGE between 4.8Vand 5.4V.

8. Vary the potentiometer P2 to increase the value of Collector-Emitter voltage VCE from 0 to 35V in steps. In Table 5, record the Collector-Emitter voltage VCE and the corresponding Collector current IC for each measured value observed.

9. Rotate the potentiometer P2 in the full counterclockwise position and potentiometer P1 in the full clockwise position.

10. Repeat steps 1 through 6 with a different gate voltage VGE set.

11. Plot and graph the IC vs VCE curve using the measured values, appropriately scaled. The curve depicts the IGBT characteristics.

Table 5: IGBT Measured Values

Image 5: IGBT I vs V Curve

Power Electronics Student Lab Manual

Experiment 6:

Characteristics of a DIAC

Introduction:

The Diode for Alternating Current (DIAC) is a diode that conducts after its breakover voltage has been met. After this, the DIAC experiences a drop in voltage with an increase in current. It is a bidirectional device and sometimes referred to as a symmetrical trigger diode due to its I-V characteristics. This lab will cover the characteristics of a DIAC and show the symmetrical relationship mentioned.

Pre-Lab Questions:

1. What distinguishes a DIAC from an ordinary diode?

2. What is the DIAC circuit symbol?

3. What is the typical breakover voltage for the DIAC used in this lab?

Apparatus Required: Quantity

Resistance 1KΩ, 5W (on board) 1

DIAC DB3 (on board) 1

Potentiometer 4.7KΩ (on board) 1

Multimeter 2

Patch Cord 6

Circuit Diagram:

The circuit below can be used to plot the characteristics of a DIAC.

Figure 6

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Power Electronics Student Lab Manual

DIAC Voltage V

and Current I

(mA)

No.

8910

Procedure:

1. Connect the circuit, as shown in Figure 6, using patch cords.

2. To plot the IA-VA characteristics proceed as follows.

3. Rotate potentiometer P1 in the full counterclockwise position.

4. Connect voltmeter at point ‘3’ & ground to read voltage VA.

5. Connect ammeter between points ‘1’ & ‘2’ to measure current IA.

6. Connect the circuit to +35V.

7. Switch Power ON

8. Increase DIAC voltage VA by varying the potentiometer P1. In Table 6, record the observed measured voltage values VA and the corresponding current values IA.

9. Rotate potentiometer P1 in the full counterclockwise position.

10. Switch Power OFF

11. Connect the circuit to -35V.

12. Switch Power ON.

13. Increase DIAC voltage VA by varying the potentiometer P1. In Table 6, record the observed measured voltage values VA and the corresponding current values IA.

14. Plot and graph the IA vs VA curve for both the +35V circuit and -35V circuit.

Table 6: DIAC Measured Values

Image 6: DIAC I vs V Curve

Power Electronics Student Lab Manual

Experiment 7:

The IA - VA Characteristics of a TRIAC

Introduction:

The Triode for Alternating Current (TRIAC) is a three terminal component able to conduct current in both directions, when the gate is triggered. A TRIAC is composed of a thyristor which makes it similar to an SCR. However, an SCR can only conduct current in one direction. A TRIAC can function as a switch for alternating

current. Lamp dimming, motor control, and electric heaters are just a few of its applications. This lab will cover the

IA-VA characteristics of a TRIAC and show the bidirectional current control.

Pre-Lab Questions:

1. How are a TRIAC and a DIAC alike?

2. How are they different?

Apparatus Required: Quantity

Resistance 510Ω, ¼ W 1

Resistance 2.2KΩ, 5W (on board) 1

TRIAC BT136 (on board) 1

Potentiometer 4.7KΩ (on board) 2

Multimeter 4

Patch Cord 10

Circuit Diagram:

The circuit below can be used to plot the characteristics of a TRIAC.

Figure 7

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Power Electronics Student Lab Manual

Vol tage V

and Current IA (mA)

No.

= _______

IG = _______

= _______

Procedure:

1. Connect the circuit, as shown in Figure 7, using patch cords.

2. To plot the IA-VA characteristics proceed as follows:

3. Rotate potentiometer P1 in the full counterclockwise position and P2 in the full clockwise position.

4. Connect voltmeter at point ‘6’ and ground to measure VG and at point ‘3’ and ground to measure VA.

5. Connect one ammeter between points ‘1’ & ‘2’ to measure current IA. Connect a second ammeter between points ‘4’ & ‘5’ to measure gate current IG.

6. Connect circuit to +35V.

7. Switch Power ON

8. Vary potentiometer P2 to set the gate current IG to a value between 0 - .5mA.

9. Increase anode voltage VA gradually by varying potentiometer P1.

10. Observe the current IA in the anode circuit. In the initial stage the measured value is nearly zero.

11. If this does not happen, repeat the steps 8 through 10 with a slightly higher gate current IG set.

12. Experiment with different Gate current values to re up the TRIAC.

13. When the TRIAC res on, record the measured VA voltage value and the corresponding measured IA current value in Table 7.

14. Rotate potentiometer P1 in the full counterclockwise position.

15. Connect the circuit to -35V and repeat from steps 7 through 13 and record the measured values on Table 7A.

16. Plot and graph the IA vs VA curve for both +35V circuit and -35V circuit.

Table 7A: TRIAC Measured Values (+35V)

Power Electronics Student Lab Manual

Vol tage V

and Current IA (mA)

No.

IG = _______

Table 7B: TRIAC Measured Values (-35V)

Image 7: TRIAC I vs V Curve

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Power Electronics Student Lab Manual

Experiment 8:

Characteristics of a PUT

Introduction:

The Programmable Unijunction Transistor (PUT) is a three-terminal component, like a UJT. However, in a PUT

the peak voltage and intrinsic standoff ratio can be controlled using external resistors. A PUT is used for relaxation

oscillators, thyristor ring, and timing circuits. This lab will cover the characteristics of a PUT, and it will go over

how the voltage peak and intrinsic standoff ratio can be programmed.

Pre-Lab Questions:

1. What is the mathematical formula to determine the peak voltage of a PUT?

2. Given the predetermined gate voltage, for this lab, what should be the peak voltages for each run?

3. Looking at the circuit for this lab experiment, explain how the resistors control the peak voltage?

Apparatus Required: Quantity

Resistance 2.7KΩ, ¼ W 1

Resistance 10KΩ, ¼ W (on board) 1

Resistance 2.2KΩ, 5W (on board) 1

PUT 2N 6027 (on board) 1

Potentiometer 4.7KΩ (on board) 2

Multimeter 3

Patch Cord 14

Circuit Diagram:

The circuit below can be used to plot the characteristics of a PUT.

Figure 8

Power Electronics Student Lab Manual

Vol tage V

A and Current IA (mA)

123

789

No.

VG = _______

Procedure:

1. Connect the circuit, as shown in Figure 8, using patch cords.

2. To plot the PUT characteristics proceed as follows:

3. Rotate potentiometers P1 and P2 in the full clockwise position.

4. Connect the rst ammeter between points ‘1’ and ‘2’ to measure Anode current IA (mA). Connect the second ammeter between points ‘4’ and ‘5’ to measure Gate current Ig (mA).

5. Connect voltmeter at point ‘3’ and ground to measure the Anode voltage VA.

6. Connect voltmeter at point ‘6’ and ground to measure the Gate voltage VG.

7. Switch Power ON.

8. Vary potentiometer P2 to set Gate voltage VG to a constant value (2.0V, 5.0V, 10V).

9. Vary potentiometer P1 to increase the anode voltage VA from 0 to 15V in steps. In Table 8, record the measured Anode voltage VA value and corresponding Anode current IA value at each step.

10. Rotate potentiometer P2 in the full counterclockwise position.

11. Set the Gate voltage VG to a different value and repeat steps 6 through 7.

12. Plot and graph the VA vs IA curve.

Table 8: PUT Measured Values

Image 8: PUT V vs I Curve

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