A generator is a rotating machine that converts mechanical energy into electrical energy. During the energy conversion process, there is energy loss. For an electric excitation generator, there are mainly the following five losses. The first is the copper loss of the stator, which accounts for about 45% of the total loss. About %; followed by the iron loss of the stator, accounting for about 20%; third, the copper loss of the rotor, accounting for about 20%; then mechanical loss, mainly wind wear loss, accounting for about 10%; and finally the excitation loss , accounting for about 5%.