Label: UPS power supply is usually selected according to the requirements of equipment power supply reliability, functional requirements, and ease of use. We generally choose different types of UPS according to different load characteristics. Probably starting from the practicality and convenience of selection, it can be divided into three categories: 1. Single operation, backup operation; 2. Bypass conversion and no bypass conversion; 3. Normal inverter operation. Usually the mains is running. If subdivided a bit further, it can also be divided into the following six categories: 1. Single-run UPS power supply, used for general important loads; used for input, output frequency is different, or has little effect on the mains, and has little effect on the frequency. Loads that require high accuracy. 2. Backup operation UPS power supply, using multiple non-power-off devices, has a backup function, when part of the failure occurs, other normal parts to supply power to the load, used for particularly important loads. 3. There is a bypass conversion UPS power supply, and the load can be supplied by the mains and inverter, which improves the reliability of power supply. Most UPSs are bypassed. 4. There is no bypass conversion UPS power supply, which is used for loads with different input and output frequencies, or with extremely high requirements for mains frequency and voltage accuracy. 5. Normally the inverter is running, and the load has high requirements on the quality of the power supply, and it is not affected by the mains, power supply voltage and frequency. 6. Normally, the mains operation, the load does not require high UPS power quality, high reliability requirements, and high efficiency without conversion. The three operating modes are combined and applied according to the nature of the load.