OPERATION OF SCR

 Silicon controlled rectifier (SCR)

It is also called as thyristors.it is used to high power applications. 

Operation of SCR

A silicon controlled rectifier is a four layer soid state current controlling device.the SCR are mainly used in electronic device.that required control of high voltage and power.

On SCR conducts when a gate pulse is applied to it. It just like a diode.

It has four layers  of semiconductor that forms to structure namely NPNP and PNPN and.it has three junction J1,J2, andJ3. 

It has three terminals anode,cathode,and gate terminal

SYMBOL OF SCR

The anode connect to the P type material and cathode are connected to the N type material. And P is connected to bottom side of P material. 

These are having two modes of operations are there:

Forward blocking mode(off state):

In this type of operation the anode of SCR is connected to the positive terminal of battery and cathode is connected to the negative terminal of the battery. And gate terminal is open circuit.

In this operation the junction J1 and J3 are in forward bias and the junction J3 is in reverse bias .then the SCR will as off state.and it is called as forward blocking mode.

                Forward blocking state diagram 

Conducting mode(on state):

In this type of operation the gate terminal is gate closed. When we are giving the positive pulse to the SCR gate terminal. The immediately junction J2. Will be breakdown. Then the SCR is on state.

               Reverse blocking state 

                   Characteristics of SCR