Temperature is a key parameter in designing electrical machines. Common models that are used for the calculation of the temperature inside the machine's components can be considerably complicated. Depending on the application of the electrical machine, a certain level of accuracy in the model must be achieved. This work provides a basic guideline for modeling the thermal behavior of electrical machines especially for the applications with varying load conditions. Since temperature measurements for various working points of the electrical machines is very time consuming, usage of the thermal model to simulate the temperatures can be time saving. Moreover, a precisely parameterized thermal network can be used as a tool for designing similar machines to achieve higher power densities.