This project focuses on the development of a mathematical model to describe how the electric arc of a circuit breaker behaves. The mathematical models will be based on Cassie-Mayr and the modified version of it; Schwarz-Avdonin. First the mathematical models have been derived and thereafter implemented into the software Simulink to conduct an analysis of how the models act. Hereafter an implementation of the models has been made into the software PowerFactory with the wish to make a transient analysis of an offshore wind power plant. In conclusion it was possible to develop mathematical models to describe the behavior of the electric arc, however, more work needs to be conducted before it is possible to make a transient analysis in PowerFactory.