Thyristors.ppt - Thyristor Devices Silicon Controlled Rectifiers(SCR By Dr Javed Iqbal Class BSc EE F-17 Army Public College of Management and Sciences

Thyristors.ppt - Thyristor Devices Silicon Controlled...

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Thyristor Devices Thyristor Devices Silicon Controlled Rectifiers (SCR) Silicon Controlled Rectifiers (SCR) By: Dr. Javed Iqbal By: Dr. Javed Iqbal Class: BSc. EE, F-17 Class: BSc. EE, F-17 Army Public College of Management and Sciences, Rawalpindi Army Public College of Management and Sciences, Rawalpindi 1
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Power Semiconductor Switches Power Diodes Power Transistors Thyristors 2 layer device 3 layer Device 4 layer Device Thyristor devices can convert and control large amounts of power in AC or DC systems while using very low power for control. Thyristor family includes 1- Silicon controlled switch (SCR) 2- Gate-turnoff thyristor (GTO) 3- Triac 4- Diac 5- Silicon controlled switch (SCS) 6- Mos-controlled switch (MCT) 2
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INTRODUCTION SCR is most popular of thyristor family due to its Fast switching action , small size and high voltage and current ratings. It is commonly used in power electronic applications. SCR has 3 terminals (gate provides control) SCR is turned on by applying +ve gate signal when anode is +ve with repect to cathode. SCR is turned off by interrupting anode current. 3 PNPN structure Symbol
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TWO TRANSISTOR MODEL OF SCR 4 Gate requires small positive pulse for short duration to turn SCR on. Once the device is on, the gate signal serves no useful purpose and can be removed.
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SCR CHARACTERISTIC CURVE 5
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IDEAL CHARACTERISTIC OF SCR 6
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