Accurately calculating the load is the primary task when selecting the capacity of a generator set. It is necessary to conduct statistics on all electrical equipment that needs to be connected to the generator set and clarify their power. For example, in an office setting, devices such as computers, printers, and lighting fixtures have different power levels. The basic load power is obtained by adding the power of these devices. However, it should be noted that some devices may generate much larger starting currents during startup than during normal operation, such as motor devices, where the starting current may be 3-7 times the normal operating current. Therefore, when calculating the load, the starting current of the equipment must be taken into account, and the empirical coefficient method can be used to estimate the starting current, in order to obtain a more accurate total load demand.

Reserving a certain power margin is also crucial. Long term full load operation of the generator set will affect its lifespan and performance, and it is generally recommended to reserve a power margin of 10% -20%. Assuming a total power demand of 800 kW is calculated through load calculation, and a 15% margin is reserved, a generator set with a capacity of approximately 920 kW needs to be selected. In practical use, this can not only meet the current electricity demand, but also cope with possible temporary load increases, ensuring the stable operation of the generator set.

At the same time, the changing trend of electricity demand also needs to be considered. If it is used in a factory, with the expansion of production scale, the number of electrical equipment may increase. Therefore, when selecting the capacity of the generator set, it is necessary to estimate the growth of electricity consumption in the next few years and appropriately increase the capacity of the selected generator set. On the contrary, if it is for short-term emergency use, such as temporary construction sites, the capacity can be accurately selected based on the fixed electrical equipment during the construction period, without the need for excessive reserve to save costs.

In addition, the actual output power of different types of generator sets also varies. For example, diesel generator sets and natural gas generator sets may have slight differences in actual output power under the same nominal capacity due to different energy conversion efficiencies. When selecting, it is necessary to refer to the technical parameters provided by the manufacturer and combine them with the actual electricity demand to choose the most suitable type and capacity of generator set.

In short, the reasonable selection of generator capacity requires comprehensive consideration of multiple factors such as load calculation, power margin, trend of electricity demand changes, and generator type. Only in this way can we ensure that the selected generator set can meet the current electricity demand and adapt to future changes, operate stably and efficiently, and provide reliable power guarantee for electrical equipment.