Tripp Lite's SU12000RT4UHW SmartOnline Hot-Swappable Modular Rack/Tower UPS System provides 12,000VA (12kVA) on-line, double-conversion UPS support for server, network and telecommunications equipment. Maintains battery-derived AC output during blackouts with active, full-time power conditioning. Fault-tolerant auto-bypass prevents unexpected service interruptions during overload or internal fault conditions. 4U power module and 4U external battery pack installs in 8 rack spaces (8U). Maintains full-time sine wave output within 3% of selectable 208/120 or 240/120V AC. Corrects brownouts and overvoltages from 65V to 140V (L-N). Detachable hardwire input & output backplate with manual bypass switch enables hot-swap UPS replacement without powering off connected equipment. Expandable runtime with optional external battery packs. Converts raw input from AC to DC, then resynthesizes output power back to perfect sine wave AC output.