Electrical Engineering ⇒ Topic : Core losses and friction losses

The core losses and friction losses are supplied from the mechanical power developed by the machine. They are put into a single group called mechanical losses or more generally, stray-power losses. when a generator or motor runs at a fixed speed and generates a given voltage, the stray-power loss is constant regardless of the electrical output or input of the machine for speed and flux density are the only factors that influence the stray-power loss.

The electrical losses are supplied from the electrical power generated by or delivered to the machine, as the case may be. Of these, the shunt filed loss is somewhat, though not entirely independent of the load, while the remaining electrical losses are nearly proportional to the square of the load current. Fig. (a) shows the combined power flow diagram for motor or generator action which is self-explanatory.

                                                       Fig. (a) Combined power-flow diagram for motor or generator action.