There are many classification methods for generator sets, which can be classified into high, medium, and low-speed units based on the rated speed of the engine; According to the rated power output of the unit, it can be divided into large, medium, and small units; According to the output voltage frequency of the generator set, it can be divided into AC generator set (intermediate frequency 400Hz, power frequency 50Hz) and DC generator set. When the voltage frequency is 50Hz, the calibration voltage of small and medium-sized generators is generally 400V (three-phase) or 230V (single-phase), and the calibration voltage of large generators is generally 6.3-10.5k/V. However, the more commonly used classification method is based on the type of fuel used in the internal combustion generator set, control mode, purpose, and appearance structure.