HV auxiliary transformer and excitation transformer in a large hydropower station are tripping because of high temperature

and the reliability of tripping circuit is directly related to the safe and stable operation of the unit. As the automatic components are put into operation for a long time

the failure frequency of the temperature control box and temperature probe increases. Due to the unreasonable design in the tripping circuit due to high temperature

the failure of these automatic components may lead to the wrong exit and directly cause non-stop accident of the unit. By analyzing the existing problems of the original tripping circuit

two optimization schemes for the circuit are proposed

the advantages and disadvantages of these two schemes are compared

and the suitable scheme for the hydropower station is given.