what should i do after addin g circuit breaker to model , results stop and became strange?

i have a simple model in simulink contain electrical source connected to induction motor in discrete mode , and it run correctly with no problem but when i connect circuit breaker between them it run correctly when circuit breaker is closing and after it open, simulation stop and the signals became strange in shape after circuit breaker open and this happens with no errors and every thing seems ordinary , i tried ti change solver type and tried all of them but with the same results...is the problem in the circuit breaker or what should i do?.....thanks for all