LECTURE 6LECTURE 6

SCRSCREngr.Shehzad Taj MeoEngr.Shehzad Taj Meo

engrshehzadtajmeo@gmail.comMob#03326345229Mob#03326345229

COMSATS Institute Of Information COMSATS Institute Of Information Technology AbbottabadTechnology Abbottabad

Aaj ki HadithAaj ki Hadith Abu Hurairah  (RadhiAllahu anhu) reported:Abu Hurairah  (RadhiAllahu anhu) reported:

The Messenger of Allah (Sallallaahu 'alaihi wasallam) said:The Messenger of Allah (Sallallaahu 'alaihi wasallam) said:

"Every Muslim has five rights over another Muslim (i.e., he has to perform "Every Muslim has five rights over another Muslim (i.e., he has to perform five duties for another Muslim):five duties for another Muslim):1) To return the greetings,2) To visit the sick,3) To accompany funeral processions,4) To accept an invitation,5) To respond to the sneezer [i.e., to say: `Yarhamuk-Allah (may Allah bestow His Mercy on you),' when the sneezer praises Allah].''[Al-Bukhari and Muslim]Riyad-us-Saliheen – Hadith No. 895

3

ThyristorsThyristors Most important type of power semiconductor Most important type of power semiconductor

device.device. Have the highest power handling capability. They Have the highest power handling capability. They

have a rating of 5000V / 6000A with switching have a rating of 5000V / 6000A with switching frequencies ranging from 1KHz to 20KHz.frequencies ranging from 1KHz to 20KHz.

Is inherently a slow switching device compared to Is inherently a slow switching device compared to BJT or MOSFET.BJT or MOSFET.

Used as a latching switch that can be turned on Used as a latching switch that can be turned on by the control terminal but cannot be turned off by the control terminal but cannot be turned off by the gate.by the gate.

4

SCRSCRSymbol of Silicon Controlled RectifierSymbol of Silicon Controlled Rectifier

5

Two Transistor Model of SCRTwo Transistor Model of SCR

6

V-I V-I CharacteristicCharacteristic

ss

7

Effects of gate currentEffects of gate current

DiodesDiodes Diode Product RangeDiode Product Range

ThyristorsThyristors

10

Thyristor TypesThyristor Types Phase-control Thyristors (SCR’s).Phase-control Thyristors (SCR’s). Fast-switching Thyristors (SCR’s).Fast-switching Thyristors (SCR’s). Gate-turn-off Thyristors (GTOs).Gate-turn-off Thyristors (GTOs). Bidirectional triode Thyristors Bidirectional triode Thyristors

(TRIACs).(TRIACs). Reverse-conducting Thyristors Reverse-conducting Thyristors

(RCTs).(RCTs).

11

Advantages over BJTsAdvantages over BJTs Higher voltage blocking capabilities.Higher voltage blocking capabilities. High on-state gain.High on-state gain. High ratio of peak surge current to High ratio of peak surge current to

average current.average current. A pulsed gate signal of short duration A pulsed gate signal of short duration

only is required.only is required.

Power Semiconductor Power Semiconductor Devices, their Symbols & Devices, their Symbols &

CharacteristicsCharacteristics

12

13

Gate Triggering MethodsGate Triggering Methods- Efficient & reliable method for turning - Efficient & reliable method for turning

on SCR.on SCR. TypesTypes

R - Triggering.R - Triggering. RC - Triggering.RC - Triggering.

14

R-TriggeringR-Triggering

Resistance firing Resistance firing circuitcircuit

LOAD

v Oa b

i R1

R2

D

R Vg

VTv = V sin tS m

EquationsEquations

17

RC TriggeringRC Triggering

RC half-wave trigger circuitRC half-wave trigger circuit

LOAD

v O

R

C

VT

v =V sin tS m

D2

VC

+

-D 1

How to off SCRHow to off SCRThere are two methodsThere are two methodsAnode current InterruptionAnode current InterruptionForced CommutationForced Commutation

Assignment using SCRAssignment using SCR Displaying the wave-form of a phase control amplifier with resistive load.

matlab Design a security system using LIMIT switch or Reed switch for doors and

windows. SCR Mini Power Inverter (any ono) Design a over voltage protection circuit using SCR. matlab Design a circuit for emergency light in which when you want to charge battery

lamp use AC source. But as you remove AC source lamp glow using battery. multisim

Uploading date 27-10-2013

Different Project typesDifferent Project types http://www.gobookee.org/http://www.gobookee.org/

get_book.php?get_book.php?u=aHR0cDovL3d3dy5rcmVzdHRlY2hu=aHR0cDovL3d3dy5rcmVzdHRlY2hub2xvZ3kuY29tL1Byb2plY3QtTGlzdHub2xvZ3kuY29tL1Byb2plY3QtTGlzdHMvS3Jlc3QtJTIwRUVFLU1pbmktUHJvaMvS3Jlc3QtJTIwRUVFLU1pbmktUHJvamVjdHMucGRmCkVFRSBFTUJFRERFRmVjdHMucGRmCkVFRSBFTUJFRERFRCBNSU5JIFBST0pFQ1QgLSBLcmVzdACBNSU5JIFBST0pFQ1QgLSBLcmVzdA====