Liebert STS2 SR 400A

For maximum availability applications, Liebert STS2 SR static transfer switch provides an automatic, seamless transfer between your critical load and the outputs of two independent UPS systems in a dual-bus power configuration. If the primary UPS should fail, the switch will automatically transfer the loads to the alternate UPS.


  • Automatic switching for dual bus loads
  • Patented Optimized Transfer option
  • Matches first generation Liebert STS1 footprint while optimizing conduit landings
  • Accepts existing Liebert STS1 ancillary accessories and sidecar cabinets
  • Offers primary or secondary side switching
  • 100% rated, fuseless design
  • Top and bottom cable entry/exit
  • Unity communication network card


  • Operates efficiently Compact, space-saving design
  • Ideal replacement for first generation Liebert STS1 switches
  • Optimized transfer algorithm ensures smooth, safe power switching
  • Internal CANBUS protocol: high-bandwidth communication between system components via twisted-pair cables.
  • Triple redundant logic with dual power feeds.
  • Standard on-unit monitoring and optional centralized monitoring capability provide continuous system visibility.
  • When applied as primary side switching, cost are lower due to requiring only one power distribution unit, a lower current due to 480V vs. 208V, and lower installation and wiring cost.