The central element of a ship power system model is typically a circuit model. This level of modeling has been valuable in evaluating architectures for future electric ships as it provides initial power flow and stability information as well as performance specifications, perhaps most notably overall efficiency. This circuit model is typically the middle layer in what is a three layer approach. At the more basic level, the physics of the components and processes is captured. In a power system, there are interactions among the electromagnetic, mechanical, and thermal behaviors. The third level is even more approximate than the circuit level. It includes such models as cost-of-ownership models, models of physical layout and integration of the power system with the balance of plant. These models are critical in the design process and depend on the circuit model to specify components and their interconnections. Incorporating breakdown physics demonstrates the linkage between the basic physics and the circuit models. Rotor dynamics provides examples of phenomena that cannot be captured in a circuit model. The design of insulation systems is an example of a field in which the circuit modeling may lead to less costly electrical systems for future electric ships.