An offlineUPS operates in two main modes: normal mode and backup mode. In normal mode, the device supplies power directly from the wall outlet to the connected devices, bypassing the battery. When a power outage or voltage fluctuation occurs, the offlineUPS detects the issue and automatically switches to backup mode, drawing power from its internal battery to keep the devices running. This transition is typically seamless, though there may be a brief moment of interruption known as a "ride-through" or "transfer time," which is usually measured in milliseconds.
OfflineUPS systems are commonly used in home and small office environments to protect sensitive electronics such as computers, routers, and other critical devices from power surges, sags, and outages. They are particularly suitable for applications where continuous power is not absolutely essential, or where the cost of an online UPS is prohibitive. However, they are not ideal for environments requiring constant power, such as data centers or medical facilities, as they lack the advanced features of online or line-interactive UPS systems.
Key components of an offlineUPS include the battery, inverter, charger, and control circuitry. The battery stores electrical energy, the inverter converts DC power from the battery into AC power for connected devices, and the charger ensures the battery remains fully charged when the main power is available. The control circuitry manages the switching between normal and backup modes, as well as monitoring the power quality.
When selecting an offlineUPS, factors such as runtime, power capacity (measured in VA or watts), and compatibility with connected devices should be considered. Runtime refers to the amount of time the UPS can sustain connected devices on battery power, which depends on the battery capacity and the load. Proper sizing ensures that the UPS can handle the total power requirements of the connected equipment without overloading. Regular maintenance, including battery checks and firmware updates, is essential to ensure reliable operation and extend the lifespan of the device.