UPS (Uninterruptible Power Supply)

A UPS (uninterruptible power supply) is a system that provides instant backup power to IT equipment when utility power fails or fluctuates, bridging the gap of typically 10-60 seconds until diesel generators start and stabilize. Data center UPS systems use large battery strings — increasingly lithium-ion instead of valve-regulated lead-acid — or flywheels, sized for 5-15 minutes of runtime at full load. Double-conversion online UPS topology, which continuously rectifies and re-inverts power, is standard in critical facilities and also conditions power quality. UPS capacity is measured in kVA/kW and deployed in N+1 or 2N configurations. Modern modular UPS units reach 97-99% efficiency in eco-mode, and UPS losses are a meaningful component of facility PUE.