The polyphase model can be used to simulate the terminal and internal electromagnetic response of, for example, Powerformer(TM): a new power generator. The circuit parameters are based on geometrical and material data. The slot leakage is modeled by means of a reluctance circuit, which is coupled to the electric circuit by means of winding templates. The capacitive current and its losses in the outer semiconducting layer of the cable are modeled with a simplified version of an RC model that has been used previously for other coaxially insulated windings. The eddy current losses were neglected; however, it is presented how they can be included in the, model. The simulated frequency and transient response of the lumped circuit is compared with measurements on an 11-MVA/45-kV, 600-r/min hydro Powerformer. With exception of the damping, the agreement is good, qualitatively, up to 100 kHz.