Modes of Operation in SCR
In SCR there are three junctions J1, J2 and J3 . These junctions play a very important role in the operation of SCR. Depending on whether the junctions are forward biased or reverse biased, the SCR will either conduct the current or will not be conduct. For SCR to conduct current, all the three junctions must be forward biased. If any one of the junctions is reverse biased the SCR will not conduct any current and hence acts as an open switch. This can be explained by considering the following cases,
- Reverse Blocking: In this Case the Positive Voltage is given to Cathode and Negative Voltage is given to Cathode and Gate is Open Circuited. In this case, the junction J1 and J3 are reverse biased, whereas J2 is forward biased. As the Junctions J1 and J3 are reverse biased so there will be no Current, But there will be Small leakages in the Forward Junction J2 As the leakage current is Very Small which will not Turn on SCR. Hence the SCR will be in OFF State.
- OFF State Forward Blocking mode: In this case, Positive Voltage is Given to Anode and Negative Voltage is Given to the Cathode and Gate is Open Circuited. The junction J2 is reverse biased, whereas junctions J1 and J3 are forward biased, Because of the Reverse Bias Voltage the Width of the Depletion Region which Block the Flow of Current Between J1 and J3.Again due to which the SCR does not conduct and acts as an open switch.
- ON State Conduction mode: The SCR will Conduct Current By Increasing Forward Bias Voltage Above the Break Down Voltage and By Applying Positive Voltage at gate terminal. In this case, all the three junctions are forward biased and hence SCR gets turned ON and starts conducting. Here, the SCR acts as a closed switch.
Hence, from the above analysis, it is clear that all the three junctions play important role in the operation of SCR and they all must be forward biased in order to turn ON the SCR.
Silicon Controlled Rectifier
The SCR or thyristor is one type of semiconductor device and using in high-power switching applications is exceptionally planned. The working of this device should be possible in a switching mode only and acts as a switch. When the SCR is triggered by its gate terminal into the transmission, then it will supply the current constantly. While planning a SCR or Thyristor circuit, exceptional focus ought to be expected for enacting the circuit. This article examines various techniques for SCR setting off or SCR turn ON strategies or setting off of Thyristors. There are different setting off strategies are accessible in light of different substances which incorporate temperature, voltage, and so on.
Table of Content
- Silicon Controlled Rectifier
- Key Terminologies
- Construction
- Operation
- Modes of Operation
- Types
- Advantages of SCR