Abstract：In view of the lack of flexibility in the input and exit of the current metal sheath loop suppression

device for high voltage cables，the problems such as excessive induced voltage of the sheath and excessive power

loss were not considered when determining the suppression impedance value，a loop suppression device was

designed which could dynamically input or exit the loop suppression impedance of the sheath according to the field

conditions. Firstly，the structure and operation flow of the suppression device was described. Then，the variation

characteristics of sheath circulation，induced voltage and sheath loss when the suppression impedance was pure

resistance，pure inductance and combined resistance inductance were analysed. On this basis，an optimization

model was established to solve the optimal impedance value which can minimize the power loss when meeting the

requirements of sheath circulation and induced voltage. Based on the optimal impedance value，the parameters of

thyristors and other components were configured. The results show that the proposed method can obtain the optimal value of cable suppression impedance that meets the engineering requirements，and achieve a good circulation suppression effect.

      Key words：high voltage cable；sheath circulation；suppression device；optimum impedance；optimization model；parameter configuration