Why does it take some time to start the standby power supply after the power failure in the hospital?

UPS (uninterruptible power supply) can be used to prevent sudden power failure, and it can also supply power for a period of time after power failure. UPS (Uninterruptible Power System/Uninterruptible Power Supply) is a system device that connects storage batteries (mostly lead-acid maintenance-free storage batteries) with the host computer and converts DC power into commercial power through module circuits such as host inverter. It is mainly used to provide stable and uninterrupted power supply for a single computer, computer network system, electromagnetic valve, pressure transmitter and other power electronic equipment. When the mains input is normal, UPS will stabilize the mains and provide it to the load. At this time, UPS is an AC mains voltage regulator, and it also charges the battery in the machine. When the power supply is interrupted (power failure), UPS will immediately provide 220V AC power to the load through the inverter zero switch method to keep the load working normally and protect the hardware and software of the load from being damaged. UPS equipment usually provides overvoltage or undervoltage protection. Uninterruptible power supply is used to deal with the following situations that may occur in the power grid: power failure (the power grid stops working and there is no voltage output), voltage drop (also called sudden drop, the voltage exceeds 10% for several seconds), continuous undervoltage, continuous overvoltage, line noise (radio frequency or electromagnetic interference caused by poor line shielding), frequency drift (frequency deviation of the power grid caused by generator instability) and switching transient (also called transient). Sometimes it can be as high as 20000 volts, but the duration is very short, only a few nanoseconds) harmonics (the interference of AC sine waves generated by electrical equipment with nonlinear characteristics in the power grid)