Eaton Power Xpert 9395C Installation And Operation Manual

Eaton Power Xpert 9395C UPS Installation and Operation Manual 164000821—Rev 06 97Figure 59. Path of Current through the UPSs in Online Mode – Distributed BypassMain Power FlowUPS 1UPS 2BatteryUPS Input Tie CabinetUPS 1 OutputUPS 2 OutputBatteryClosedOpenBreakers Output toCritical Load66..44..33 BByyppaassss MMooddee –– DDiissttrriibbuutteedd BByyppaassssIn Bypass mode, the output of the system is provided with three-phase AC power directly from the bypassinput. While in this mode, the output of the system is not protected from fluctuations, spikes, or poweroutages from the source. No battery support is available to the output of the system in the Bypass mode ofoperation.The distributed bypass system automatically switches to Bypass mode if it detects a UPS system overload orload fault. If one UPS becomes unavailable, the distributed bypass system dynamically updates the redundancycalculation to determine if the remaining UPSs can support the load. If the load can be supported, the systemdoes not switch to bypass.Figure 60 shows the path of electrical power through the parallel system when operating in Bypass mode.In a distributed bypass system, each UPS operates similar to a single UPS, but in parallel with each other. Thebypass source for the load is derived from the bypass input of one, two, three, or four UPSs, depending on thesystem configuration, through the internal static switches. If a module is taken offline, the other modulesremain online to support the load. If more modules than can support the load must be taken offline, the loadmust be transferred to maintenance bypass or shut down.Understanding UPS Operation