Over Voltage Protection of Semiconductor

• When the SCR is turned on , its maximum voltage rating must be less than the specific rating of the SCR. 
• There are following main reasons for generation of over voltage or transient voltage.

      ( 1 ) Commutation of the SCR

      ( 2 ) Main switching, main supply, lightning surge voltage

      ( 3 ) Inductive load

• The rating of the SCR must be greater than the 2 to 2.5 times off state voltage in order to protect SCR against transient voltage. 

There are following circuits used in order to protect SCR. 

• The over voltage protection of semiconductor devices is achieved by

      ( 1 ) Snubber circuit

      ( 2 ) Non – linear resistor

      ( 3 ) Crow bar circuit

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