Power Electronic Lab: PEDM100S : 17: Power Electronics Trainer (All Firing Circuit Circuits) POWER100 : 18: Power Electronics Trainer with different plugin Panels 19.UJT Relaxation Oscillator: PE-43 : 20.Single Phase PWM Inverter: PE-44 : 21.Power Supply for Power Electronics Boards ( + 35V, +15V 250mA) PD-01 : 2 Various configurations of UJT relaxation oscillator type 1 (low output impedance), type 2 (moderate output impedance) and type 3 (high output impedance) In built parts: An isolation transformer 230 V A.C. At 100 mA. This protects external instruments from damage if they are not isolated KCT College of Engineering and Technology Department-EE Power Electronics and Drives 1 INDEX Sr.No: Experiments 1 To study principle of operation of SCR, plot V-I characteristics and study the effect of gate triggering on turning on of SCR. 2 To draw V-I characteristics of an UJT and to use UJT as relaxation oscillator 3 To study the effect of free-wheeling diode on power factor for single Uni Junction Transistor (UJT) A unijunction transistor (UJT) is a three terminal semiconductor device with only one junction that acts exclusively as an electrically controlled switch. The unique switching characteristics of UJT makes it different from conventional BJT's and FET's by acting as switching transistor instead of amplifying the signals. The operation UJT RELAXATION OSCILLATORS When the supply voltage VC(= VE) reaches the firing potential, VP, the UJT fires and C discharges exponentially through R2until VEreaches the valley potential VV. UJT RELAXATION OSCILLATORS When VEreaches the valley potential VVthe UJT turns OFF, IEgoes to zero and the capacitor is recharged. UJT stands for U ni J unction T ransistor. It is a three terminal semiconductor switching device. The Unijunction Transistor is a simple device that consists of a bar of n-type silicon material with a non-rectifying contact at either end (base 1 and base 2), and with a rectifying contact (emitter) alloyed into the bar part way along its length UJT relaxation oscillator UJT relaxation oscillator is a type of RC ( resistor-capacitor) oscillator where the active element is a UJT (uni-junction transistor). Lab Manuals (20) LED related (3) Light Related (14) Lighting Circuits (44) MATLAB (3) Microcontrollers (12) Mobile Phone Related (3) Motor Related (14) Nanotechnology (14 Bistable multivibrator. 41 11. Monostable multivibrator. 44 12. Astable multivibrator. 47 13. Schmitt trigger. 50 14. UJT relaxation oscillator. 53 15. Blocking oscillator. 57 NOTE: A minimum of 10 (Ten) experiments have to be performed and recorded by the candidate to attain eligibility for University Practical Examination. What is relaxation oscillator? Ans: A relaxation oscillator is an oscillator based upon the behavior of a physical system's return to equilibrium after being disturbed. That is, a dynamical system within the oscillator continuously dissipates its internal energy. POWER ELECTRONICS LAB LAB MANUAL 17 EEL 58 ( 2019 - '20) Bachelor of Engineering 1. Come prepared to the lab with relevant theory about the experiment you are conducting. 2. Before switching on the power supply, make sure that the voltage knobs UJT Relaxation Oscillator 14 5 SCR digital triggering circuit for Dept of EC 4 Dr Ambedkar Institute of Technology fPower Electronics Lab Manual VII Sem EC • Set R1 and R2 to mid position and V1 and V2 to minimum. • Set the gate current