EATON Powerware® 9390 UPS (100–160 kVA) Installation and Operation Manual 164201604 Rev D www.powerware.com 7-1Chapter 7 Understanding UPS OperationThe Powerware 9390 UPS is a continuous-duty, solid‐state, transformerless (at 208,400, and 480 Vac), three-phase, true online system that provides conditioned anduninterruptible AC power to the UPS system's output. The UPS supports processcontrol, data processing, telecommunications/PBX, research, and non-patient medicalequipment. The Powerware 9390 UPS maintains power to the critical loads duringcommercial electrical power brownout, blackout, overvoltage, undervoltage, andout‐of‐tolerance frequency conditions.The basic system consists of a rectifier, battery converter, inverter, monitoring/operation control panel, integrated communication server, and digital signal processor(DSP) logic.In this manual, the power required by your equipment is called the critical load. TheUPS supplies the critical load with conditioned power that is synchronized with yourutility power. Figure 7‐1 shows the main elements of the UPS system.OutputContactorK3BatteryBatteryBreakerBatteryConverterInputContactorK1AC Input toRectifier/ChargerAC Input toBypassBackfeedProtectionContactorK5Power ModuleInverterRectifierDigitalMeteringStaticSwitchAC Outputto CriticalLoadUPS CabinetFigure 7‐1. Main Elements of the UPS SystemIf utility power is interrupted or falls outside the parameters specified in Chapter 14,“Product Specifications,” the UPS uses a backup battery supply to maintain power tothe critical load for a specified period of time or until the utility power returns. Forextended power outages, the UPS allows you to either transfer to an alternativepower system (such as a generator) or shut down your critical load in an orderlymanner.Figure
