1. The capacity safety factor of AC regulated power supply is based on the nominal rated capacity of the output apparent power (kVA), and in general, the load is not purely resistive, that is, the power factor COS ￠ ≠ 1. The actual active power output of the regulator is kW=capacity (kVA) × COS ￠. Therefore, in actual selection, it is necessary to choose a stable power supply reasonably according to the specific conditions such as the rated power, power factor, and load type of the electrical equipment. The output power should have an appropriate margin, especially when selecting impact loads, the margin should be larger. The specific selection safety factor is shown in the table below. For equipment type safety factor selection, the capacity of the stable power supply should be 1.25~1.5 for pure resistive loads such as incandescent lamps, resistance wires, electric furnaces, etc. 1.25~1.5 times the total load power for inductive and capacitive loads such as fluorescent lamps, fans, motors, water pumps, air conditioners, computers, refrigerators, etc. When selecting, the starting current of the load should be considered to be particularly large (up to 2-3 times the total load power) in environments with high inductive and capacitive loads (such as motors and computers). When selecting a regulator capacity, it should be 2.5 to 3 times the load power, as it should be 5 to 8 times the rated current. For example, when selecting a voltage regulator for one 2.2kW and one 5.5kW three-phase motor, the capacity should be ≥ (2.2kW+5.5 kW) × 2.5=19.25 kVA, which means that at least a voltage regulator with a three-phase SJW-20 kVA or higher product should be selected.

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