FEPET03 – Study of TRIAC Characteristics

FEPET03 – Study of TRIAC Characteristics

Introduction

The learning on the device characteristics is the most important part of power electronics study. The line of power electronics trainers are aimed at making the study convenient and complete. The devices are connected to a well protected circuit with digitally controlled power supplies and accurate metering. A TFT colour LCD along with encoders and switches are used for user interaction to make the setup user-friendly and convenient. The user can set the control of the digital power supplies manually or use one of the auto-plot modes to plot the V-I characteristics of the device instantly.

This setup enables the user to forget about getting the circuit to work and focus on learning the intricacies of the device characteristics. The auto-plot feature enables the user see the textbook waveforms of the V-I characteristics in an instant.

The system consists of the following:

Device Under Test – TRIAC.

Load resistor.

Programmable voltage source – Vmm.

Programmable current ource – Vg.

High resolution measurements – Vmm, Vm1m2, Vgm1.

Current measurement – It, Ig.

Trainer User Interface

The user interface of the trainer consists of a TFT LCD to display the measurements and graphs along with encoders and switches to get inputs from the user. The trainer has multiple modes of operations meant for direct display of set and measured values and also for the automatic display of waveforms.

To power up theTRIAC, programmable voltage sources, Vmm and the programmable current source Ig are also provided on board.

Operating Modes of the Trainer

Measurement Mode

In the measurement mode, all power supplies are user controlled and both set and measured voltage/ current values are displayed, enabling the user to manually adjust the parameters and view measurements.

For the power supplies Vmm, and Ig, the SET and ACTUAL values are displayed side by side on the LCD. The measurements Vm1m2,Vgm1 and It are also displayed on the LCD. The encoders and tactile switches can be used to manually adjust the power supplies and record the measurements to study the device characteristics.

TRIAC Measurement mode

Auto-Plot Mode1 – TRIAC Output Characteristics(+ve)

The TRIAC V-I characteristics(+ve) mode plots Vm1m2 (+ve) versus It (+ve) for user set values of Ig. When the AUTO PLOT switch is pressed, the Vmm voltage is varied from 0 to 25V automatically and the measured Vm1m2 and It values are plotted. Before starting this plot, user is required to set the value of zig. A maximum of five plots can be displayed on the screen simultaneously.

V-I Characteristics (+ve)

Auto-Plot Mode 2 – TRIAC V-I Characteristics(-ve)

The TRIAC V-I characteristics (-ve) mode plots Vm1m2(-ve) versus It(-ve) for user set values of Ig. The value of Ig can be either positive or negative. When the AUTO PLOT switch is pressed, the Vmm voltage is varied from 0 to -25V automatically and the measured Vm1m2 and It values are plotted. Before starting this AUTO PLOT, user has to set the Ig. A maximum of five plots can be displayed on the screen simultaneously.

V-I Characteristics (-ve)

NOTE: The Auto-Plot modes are incorporated into the system to ensure the users, most of the time students, about the proper operations of the target device and inspires them to take up the device study with confidence and ease. The users have to generate all the plots by themselves. Auto-Plot graphs are only visual reference to them and plot values are not available to the users.