A mathematical model of fault current thermal action in vacuum-breaker protected middle-voltage circuits
Dependence of Joule integral on the total time of symmetric three-phase fault circuit interruption by a vacuum circuit-breaker is analyzed via numerical solution of corresponding differential equations. A mathematical model is developed to obtain relationship between the breaker response and current distributor thermal stability in short-circuit conditions. Optimal total time of the breaker opening is calculated for the minimum value of Joule integral.