Simulation Analysis on Dynamic Protection Characteristics of Low Voltage Circuit Molded Case Breakers Based on PSCAD/EMTDC

In this paper, the electromagnetic characteristics of magnetic instantaneous acting trip in typical low-voltage molded case circuit breakers (MCCB) are analyzed using finite element analysis software ANSOFT and the electromagnetic torque on armature of magnetic trip which varied with the current and air gap are calculated and applied into motion equations of the trip. Based on the motion equations and Cassie arc model, a simulation model of MCCB is built using power system simulation software PSCAD/EMTDC to describe the dynamic behavior of the MCCB during short-circuit protection. The results of short-circuit interruption experiments verifies the accuracy of the model. It demonstrates that the simulation model has good prospect in optimizing the design and protection performance of MCCB.