Power MOSFET is a voltage controlled device? 1) Select Triac as the device under test by referring to the top RHS diagram. TRIAC Characteristics 9 3. What are the advantages of three phase rectifier over a single phase rectifier? Positive or negative potential across the terminals can be triggered by reaching +/- breakover voltage. The peak voltage applied across the device in either direction must be less the break over voltage in order to retain control by the gate. The symbol and pin out of TRIAC is shown below. You can repeat the sequence when you rotate the motor in anticlockwise direction also. The system is provided with 2 no AC switches, one for electronic control circuit. An electron movement in the n-channel, in turn causes substantial hole injection from p+ substrate layer into epitaxial n- layer. With RL- load it becomes a two-quadrant converter. A TRIAC (triode for alternating current; also bidirectional triode thyristor or bilateral triode thyristor ) is a three terminal electronic component that conducts current in either direction when triggered. Ring main system 5. Demonstrate the bi-directional conduction of a gated TRIAC. The invention of the TRIAC was necessitated because of the need for controlling power fed to ac loads. When the dimmer voltage is around 32 volts the DIAC starts conducting as indicated by M3 meter. Then a triac has four possible triggering modes of operation as follows. The term TRIAC is a genericised trademark. An SCR is a three terminal, four layer latching device. 11. A dual is used only when reversible dc drives with power ratings of several MW are required. Rate of rise of capacitor voltage can be controlled by varying ‘R’. What are the differences between SCR and TRIAC? It can operate and switch both half cycles of an AC waveform. Measure the average dc voltage across the load and rms value of the ac input voltage using g' DMM, 10. 2. 5. 3. Why? ; V DRM is the maximum repetitive peak voltage (usually the maximum peak voltage of the applied AC wave) that can be reliably tolerated. By doing this , you will be pressing limit switch of the shaft and motor will start with low speed at the start (soft start). Diode D allows the flow of current during positive half cycle only. 5. What is a three phase controlled rectifier? Explain the different working modes of operations of a TRIAC? TRIAC switch The TRIAC (Triode AC) model is designed using two anti-parallel SCR switch models as shown below. Generally power enhancement MOSFETs are used in power electronics circuits. Then throw the switch SW3 in upward position. 1 Thyristors DC Characteristics PREPARED BY: J.B. G. Ibarra 1.0 OBJECTIVES 1.1 To become familiar with the characteristics of the (SCR) silicon controlled rectifier and its operation. The various types of three-phase phase-controlled converters are 3 phase half-wave converter, 3-phase semi converter, 3-phase full controlled and 3-phase dual converter. 4. Experiment No : 2 Experiment Name : Study of V- I Characteristics of TRIAC. To obtain V-I characteristics and to find on-state forward resistance of given SCR. Does DS1 light? When the SCRs are fired at 0, Average output voltage, Vo = ( 3√3 Vm / Π ) *cosα, Vm = Peak phase voltage, Volts α = Firing angle, degrees. EXPERIMENT-1(a) V-I CHARACTERISTICS OF SCR AIM: 1. Thank you. 4. 3. CIRCUIT DIAGRAM: Fig 1.1(a) Circuit diagram for VI characteristics of SCR. 3. For reverse characteristics, change the connection to make M. 2. The TRIAC is a three-terminal device which can conduct in either direction. To plot the output waveforms for single phase dual converter. The three terminals are anode, cathode and gate. To study the characteristics of TRIAC Apparatus : INSIF TRIAC Characteristics Apparatus. Compare UJT triggering circuit with RC firing circuit? Once the gate V. For a DIAC, there is a breakover voltage present in either direction. MOSFET Characteristics 15 4. A fully controlled converter or full converter uses thyristors only and there is a wider control over the level of dc output voltage. Define Holding current, Latching current on state resistance, Break down voltage, 3. ☞Switch on Kit observe whether meter are reading 0. b) Adjust the main terminal and the gate voltage sources to +6Vdc. Demonstrate the four triggering modes of a TRIAC. 3. This makes triac circuits ideal for use in a variety of applications where power switching is needed. What are the effects of source inductance on the output voltage of a rectifier? To study Three Phase Converter (Half Wave and Full wave Bridge). d) Depress and hold S1. ☞Increase VAK voltage to maximum position. Switch on the power supply to the CRO. The device is said to be in the forward blocking state or OFF state. c) Close S2 and depress S1 momentarily. Junction’s j1, j3 are forward biased and the junction j2 is reverse biased. f) Connect the oscilloscope across DS1 to monitor the load voltage. 9. Vary the voltage applied across Gate and corresponding V, 5) The above steps are repeated for different values of I, 6) Vary the voltage across Collector and Emitter and noted down V, TRANSFER CHARACTERISTICS DRAINCHARACTERISTIC. 6. a) Examine the circuit shown in Fig. It is direct method of testing. You can observe waveforms TP2 and TP4 with Motor as load. All the eight thyristors (TYN 612) are grouped into two sections are for +ve o/p & for –ve output (4 no of each group). 1. For any one particular firing angle plot the waveforms of the ac voltage, voltage across the load and the SCR. R2 is the variable resistance. Now gradually load the motor and take ,speed, current voltage readings. 3 - SCR AC Power Control, ECE121 Experiment No. What are the advantages of three phase controlled rectifiers? The two modes of its operation are non-circulating current mode and the circulating current mode. The test point TP5 & TP6 display the ZCD waveform of the system. iv List of Experiments Exp No Experiment Nmae Page No 1 Static characteristics of SCR and DIAC. Rotate the pot P1 to zero position & turn it in clockwise direction the motor starts rotating in clockwise direction. Resistor R1 lowers Vdc to a suitable value for the zener diode and UJT. 6. Name the three regions of operation in a MOSFET. Verify the output voltage on the basis of output voltage indication. Once SCR starts conducting, it behaves like a conducting diode and gate has no control over the device. Sheet Report 1 Object Power System Components Objectives To study- 1. You may have to adjust pot marked “ADJUST” to get DC output voltage between approximately 50 volts D.C. to 175 volt D.C. You may observe the waveforms at TP1, TP2 and TP4. SCR with positive anode voltage would turn ON. characteristics by using two transistors analogy. In this system when the motor is required to be braked, the pulses for the bridge working as converter are blocked and the other bridge is operated in inverter mode. voltage between K1and K2 ,K2 and K3 ,K3 and K1), Where Emph is the peak value of phase to neutral voltage and α is the delay. The power enhancement MOSFET has an anti parallel fast turn on diode which permits reverse current of the same magnitude as that of the main MOSFET, so that drain substrate junction will not be damaged when drain and source has reverse biasing. How is the output power to the triggering circuit controlled? In the middle (marked zero position) none of the pulses for triggering the thyristors are generated. 5. Labels: diac, ece121 industrial electronics, experiment, triac, where can i get a copy of the picture of the figures? But here the controlling parameter is gate –emitter voltage VGE because IGBT is a voltage –controlled device. If JFETs are operated with reverse bias on their gate leads to prevent gate current. The nanoparticles of Triac were prepared by interfacial polymer deposition following solvent displacement, known as nanoprecipitation method, which was proposed by Fessi et al.13 Problems in formulation, delivery, and release characteristics of Triac are among the reasons for this study. Connect CRO and observe all waveforms for TP1, TP2, TP3 & TP4 for both +ve & -ve outputs, by rotating pot P1 in clockwise and anticlockwise direction respectively. In more sophisticated systems the stored mechanical energy instead of being dissipated is returned to the AC mains by using what is called as regenerative braking system for dual converters. What is commutation angle of a rectifier? 6 - UJT-SCR Time Delay Circuit, ECE121 Experiment No. For star connection one can perform the calculations using the line to line voltage measured between K1 and K2, K2 and K3 and K3 and K1. d) Look at your circuit and then record in Table 8-1 the triggering mode of Q1 in this configuration. At any time, one SCR from each half conducts when there is current flow. IGBTS are widely used in medium power applications such as dc and ac motor drives. To understand performance of SCR/TRIAC/DIAC/MOSFETS and IGBT. 7. Figure shows the quadrant operation of fully controlled bridge rectifier with R-load. b) Reverse the polarity of the main terminal voltage by reversing the power supply leads connected to your circuit. The necessary isolated DC supplies for opto isolators (8 no) are generated & an AC sensing circuit at inside is provided to achieve proper synchronization. Compare Power MOSFET’s , IGBT with BJT’s. d) Close S2 and depress S1 momentarily. 1-6 2 Static characteristics of MOSFET & IGBT. The enhancement MOSFET is used as a switch in power electronics by keeping, Switching times (turn ON and Turn Off) are very low and hence switching loss is, STUDY OF INSULATED GATE BIPOLAR TRANSMISTOR, IGBT is a new development in the area of power MOSFET technology. The switch SW3 is required to be kept in downward position for normal-dual converter operation. If thyristor does not turn off even after pot is at the highest resistance value, then reduce anode supply voltage. Its primary function is to control power bilaterally in an AC circuit. Fundamental Characteristics of Thyristors Triac Basic Operation Figure AN1001.4 shows the simple block construction of a Triac. C. Demonstrate bi-directional operation of DIAC. 10.Conduct an experiment to produce variable DC o/p voltage (chopper), plot o/p voltage v/s duty cycle for Variable frequency & Fixed Frequency. this gives rise to a full four quadrant operation for the dual converter. the power station, the transmission lines, and the distribution system. where can i get a copy of the picture of the figures? For motor to start running you have to take pot P1 to most anticlockwise position. Make the connections as per the circuit diagram. c) Adjust the gate supply voltage to 6 Vdc. b) Adjust the power supply voltage to 30Vdc. Adjust gate voltage to a slightly higher value than what is found in (a) set, Increase the anode current from latching current level with pot or by increasing the supply voltage slightly. What are the advantages of six pulse converter? To know the application of triggering circuits. Explain how synchronization of the triggering circuit with the supply voltage across SCR is achieved? Now throw the switch SW3 in downward (NORMAL) position. Fig. A rope or leather belt is wound round the pulley & its two ends are attached to two spring balances F 1 & F 2 . Yes. Three phase half controlled bridge rectifier circuit consists of three SCRs in three arms and three diodes in the other three arms. When field excitation is maintained in the same direction with change in armature voltage polarity, direction of rotation of the DC motor can be changed. g) Depress and hold S1. The armature will be disconnected from power circuit & connected to lamp load which is located on the right hand side socket. Voltage at terminal MT 2 is positive with respect to terminal MT 1 and gate voltage... Second Quadrant Operation of Triac. Keep the multiplication factor of CRO’s probe at maximum position. 5. a) Reduce the gate voltage supply to zero. Diodes ‘D1’ to ‘D4’ rectify ac to dc. V-I characteristics of TRIAC are obtained. SCR Characteristics 3 2. 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Take, speed, current voltage readings now turn OFF power circuit connect..., TRANSFER characteristics drain characteristics in delta connection calculations the advent of thyristors has completely changed picture... Is to control the TRIAC saves both space and cost in AC circuit, both the direction basis output... Only a small leakage current flows voltage controllers CRT for a DIAC with a gate for! Triggering of SCR & the same process is repeated with motor running at about 100 V with load! Effect transistors, on the terminal MT1 as the reference point operated reverse! Static characteristics of this course are made available for them ; a major in! ( π to 2π ) & triggering pulse goes on varying the smallest time interval which! At this instant is the polarity of the triggering circuit controlled are made available for them the starts... Maximum position reading 0 the introduction of thyristors other simple methods were used control. Igbt with BJT ’ s, IGBT is free from second breakdown problem present in the former only.