How to choose the power of MUST UPS power supply
The output power of the UPS is closely related to the power factor. Under the capacitive load condition, the UPS output power can reach the nominal power. Under the inductive load condition, the UPS output power is greatly reduced. Even when the power factor is 0.8 (rational), the output power can only reach 50% of the nominal power. The load of UPS is generally computer load, and the internal power supply of computer load is mostly switching power supply. Under the load condition of switching power supply, the instantaneous power is very high, but the average actual power is very small. Therefore, when the UPS is used as the load of the switching power supply, its power factor can only reach about 0.65, and the load power factor index of the UPS is generally 0.8. According to this index to drive the switching power supply load, it may damage the UPS equipment. Therefore, when selecting the power of the UPS, the power factor of the load must be considered.
UPS should not carry inductive load. Some units want to use high-power fans and air conditioners to test the performance and output power of UPS when testing the machine, which is not suitable. Some units add fans, motors, etc. to the UPS with low-power square wave output, which is not acceptable.
The UPS with backup square wave output cannot carry inductive load, and the load should be about 50% of the rated load. Because under this load condition, it can eliminate the weight of the 3rd harmonic (150Hz sine wave) in the 50Hz square wave output waveform, reduce the current flowing through the DC filter capacitor in the switching power supply, and prevent the filter capacitor from overcurrent for a long time. damage due to work.
When the backup UPS is powered by the inverter, it is generally equipped with overload and short-circuit active protection functions. However, when the mains is powered, it generally relies on stable input communication to perform the task of overload protection, so users cannot easily increase the mains power supply. Enter the volume of the secure wire. Otherwise, once the UPS output has a short-circuit accident, there may be a dangerous phenomenon that the input is safe and burns continuously, but the printed lines on the printed board are burned.
