Protection circuit for preventing thyratron transistor misoperation in SVC system

The invention relates to a protecting circuit which prevents the SVC system transistor error movement. The circuit first dose voltage signal collecting to the voltage mutual-inductor second side 100V synchronic voltage, then it dose amplifying, sum operation and filtering procession to the gathered voltage signal; it then enters into the single chip machine to do digital process and computes the electronic signal and the digital signal into the current voltage value, it compares the current voltage and the limit value to decide weather outputs the protecting value, then it uses the protecting circuit to output the protecting signal to the protecting circuit to execute the correct protect order.