When the UPS is undergoing maintenance, the normal power supply to the load equipment is ensured through manual bypass. After the maintenance operation is completed, the UPS is restarted and returns to normal operation. Extremely low maintenance rate, MTTR of 150000 hours, greatly improving the availability of UPS uninterruptible power supply.

From an application perspective, the changes in UPS functionality have gone through three stages. The first stage is hardware protection, which protects the hardware system of the load device from damage due to abnormal power or sudden power interruption; The second stage is data protection, which protects the data of load devices from being damaged or lost due to sudden power outages when the mains power is interrupted; The third stage is system availability protection, which ensures high-quality power supply to critical loads in the event of normal, abnormal, or even interrupted mains power. The changes in these three stages are all driven by the continuous increase in demand for production systems due to social development and technological progress. The first stage was highlighted in the 1970s and 1980s, shortly after the birth of UPS. The second stage was prevalent in the mid-1990s, and the third stage became increasingly important from the late 1990s. Even today, system availability remains one of the most important indicators required for UPS power supply systems in data centers, factories, hospitals, rail transit and other electric fields.