An online Uninterruptible Power Supply (UPS), also known as a double conversion UPS, is a type of UPS that provides a more stable and reliable source of power than other types of UPS.

In an online UPS, the incoming AC power is first converted to DC power, which is then used to charge the UPS battery. The battery then provides power to an inverter, which converts the DC power back into AC power that is fed to the connected devices. This process provides a constant and clean source of power, regardless of fluctuations or interruptions in the incoming power.

Online UPS systems are commonly used for critical applications, such as servers, data centers, medical equipment, and industrial machinery, where even a brief power interruption can cause significant damage or data loss.