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Example applications : Chopper & InverteroAlso known as inverter thyristors.oON-state voltage typically 1.7V for 1800V device.oExampleApplication:Variablefrequencyconverter(thyristor motor control)Gate-Turn-Off Thyristors (GTO)oCan be turn-OFF by a negative gate signal.oTurn-ON by applying short positive pulse and turn-OFF by a short negative pulse to its gate.oHigher ON-state voltage than normal SCRoON-state voltage typically 3.4V or 1200V device.oExample Application : Variable speed motor drives, High power invertersGTO thyristor valve at HVDC power station
25/8/20109Bidirectional Triode Thyristors (TRIAC)oEquivalent to2 SCR joined in inverse parallel(paralleled but with the polarityreversed) and with their gates connected together.oThis results in a bidirectional electronic switch whichcan conduct current ineither directionwhen it is triggered (turned on).oIt can betriggered by either a positive or a negative voltagebeing appliedto its gate electrodeoApplication : Household power application - light dimmers, speed controls forelectric fansReverse-Conducting ThyristorsoAnti-parallel diode connected across SCR on the same silicon chip.oRCT also called Asymmetrical Thyristor (ASCR).oLimited application : Normally in chopper (batterycharger) & inverter, AC motor speed & torquecontroller (inductive loads )
25/8/201010Static Induction ThyristorsoTurned-ONby applyingpositive gate voltage.oTurned-OFFby applyingnegative gate voltage.oLow ON-state resistance & low voltage drop.oVery fast switching speeds –Sub micro-secondswitching time (1 to 6μsec)oThe rating can go up to 2500V / 500A.oApplication : High frequency changers & invertersLight-Activated Silicon-Controlled RectifiersoTurned-on by direct light radiation on silicon wafer.oGate structure is sensitive for triggering from practical light sources.oRating could be has high as 4KV / 1500A.Light-triggered thyristor (LTT) valve used in HVDC power transmission
25/8/201011FET Controlled Thyristors (FET-CTH)oCombines a MOSFET & a thyristor in parallel as shown.oHigh switching speedsoTurned ON like conventional thyristors.