Several considerations for the selection of diesel generator set：

       1. Determination of the capacity of common diesel generating units

　　According to the long-term continuous operation output power of the unit can meet the maximum calculation load selection of the whole project, and the standby capacity of the generator set should be determined according to the importance of the load. The continuous output power of diesel engine is generally 0.9 times of the calibrated power.

　　2. Determination of the number of commonly used diesel generator sets

　　The number of commonly used diesel generator sets is usually set at more than 2 to ensure the continuity of power supply and adapt to the change of electricity load curve. Only when the number of units is large, can the number of units put into the generator set be determined according to the change of electricity load, so that the diesel engine is often run under economic load, in order to reduce the fuel consumption rate and reduce the power generation cost. The optimum economic operation of diesel engine is between 75% and 90% of the calibrated power. In order to ensure the continuity of power supply, the common unit itself should consider setting up a standby unit, so that the generator unit can still meet the important power load uninterrupted continuous power supply when the unit fault maintenance or shutdown inspection is carried out.

　　3. Determination of speed of common diesel generator sets

　　In order to reduce wear and increase the service life of the unit, medium and low speed units whose calibrated speed is no more than 1000r/min should be selected for common generating units, and medium and high speed units can be selected as standby units. Units of the same power station should be of the same model and capacity so that the same spare parts can be used to facilitate maintenance and management. Load change large project, can also choose the same series of different capacity units. The output calibration voltage of the generator is determined in the same way as that of the emergency generator set, which is generally 400V. The high-voltage generator set can be selected for projects with large individual power consumption and long transmission distance.