Hello Gustavo,
it sounds like the way you are tyring to do things could work, but that the model just isn't seeming accurate. I would first start with a single phase system and get that working as expected (you can put a single phase AC source through a single phase transformer) and focus on that. Once that is working, you can slowly build on the pieces of the larger system and see where things stop working. If you put a large resistance in series with the block, it doesn't make sense that it's current would grow indefinitely unless the simulaiton was diverging (which is possible, especially if you are using a fixed time step). It's more likely you need a large resistance in parallel with the machine, and it and the transformer need to have realistic inducances. Also, when youare having problems like this, it is helpful to put screenshots or share the files that you are working with.
Regards,
Joel
