Influence of load capacity and load power on ups and Inverter

The output capacity of UPS refers to the product of the valid value U of the output voltage and the valid value I of the output current. Power Factor cos Phi refers to the ratio of active power P output by UPS to nominal view in power S, which can be expressed as cos Phi = P/S. Cos Phi is generally 0.8, UPS requires at least 0.8 of the load power factor, of course, the higher the power factor, the better, too low, it is too waste. When the power factor is 0.8, the angle between the voltage and the current is Phi = cos-10.8 ≈ 36.9 °. At this time, there is still reactive power current going back and forth in the line, reactive Power q = U · I · sin Phi, the relationship between power S and active power P and reactive power is S = p + q = U · I · cos Phi + U · I · sin Phi. If the angle between the voltage and current is 0 °, the reactive power q = 0, active power P = U · I · cos 0 ° = U · I = S. All the UPS capacity becomes active power, and the utilization rate of UPS is the highest.

When selecting the ups and inverter models, you should know the total output capacity of the load, and also consider the load power factor to determine the standard power capacity of the ups and inverter, there must be a certain amount of wealth. Total sine wave output power: P = U · I · cos phi. The rated ups and inverter capacities are generally determined based on a 0.8 load power factor, more than 80% of ups and inverter users are computer loads, while most of the internal power supply of Computer load is switch power. Under the load of the switching power supply, the instantaneous power is very high, but the average actual power is not big. Therefore, when the ups and inverter are used as the load of the switching power supply, the load power factor can only reach 0.6 ~ About 0.65, and the ups and inverter are generally 0.8. According to this indicator to drive the load of the switching power supply, it is possible to damage the ups and inverter. Therefore, when selecting the UPS inverter power, you must consider the load power factor. Because the load power factor is difficult to calculate, we recommend that you use a 1kva ups and an inverter with two 21 inch-Color Display computers, and so on.

The inductive load has a great impact current at startup, usually about 10 times of the rated current. Therefore, the ups and inverter will experience instantaneous overload at startup. If the load is started when the UPS is working in the mains bypass power supply status, the impact on ups and inverter can be avoided. Ups and inverter power supply are generally not suitable for carrying pure inductive load. Some units use high-power adjustable speed fans, fans, and motors to test the ups performance and output power when accepting the machine. This is not suitable. Generally, V incandescent lamps can be used for load tests.