BACK EMF PROTECTION CIRCUIT OF RELAY

 Protection is assured through disconnecting power supply in a circuit by over current protection, which removes fire hazards and protect the components from burning out.  

Circuit protection, at its simplest, is the intentional addition of a 'weak link' in an electrical circuit. This link will break in the event of a fault – whenever there is high temperature, excessive current or a short circuit in a conductor, thus protecting the electrical circuit from damage. 

Circuit connection 

Description

Here we are trying to implement the protection circuit that is used to protect the opamp from back EMF when it is connected directly with the relay.

So for protection of opamp we will use transistor (BC547) for switching, this switch will turn on when the opamp will give output. At that time flow of circuit connection will be from collector to emitter due to which relay turns ON.

But we know that the coil of relay is responsible for back EMF which will move towards the transistor due to which transistor can also be damaged therefore for the protection of transistor and other components we will be using freewheeling diode which will change turn the direction of current flow from the transistor to the source connected across relay.

This is the overall working of the protection circuit used to protect components from back EMF of relay. 

 Components used

•       Torch LDR*1

•       1K resistor*2

•       Potentiometer(hg)*1

•       LM358(opamp)*1

•       5V supply

•       Ground

•       BC547(transistor)*1

•       Diode(1N40007)*1

•       Relay*1

•       Led*1