UNDERSTANDING UPS OPERATION
If 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 to the critical load for a specified period of time or until the utility power returns. For extended power outages, the backup battery supply allows you to either transfer to an alternative power system (such as a generator) or shut down your critical load in an orderly manner.
7.1Operating Modes
The UPS system supports the critical load with the following operating modes:
SNormal mode – The critical load is supplied by the inverter, which derives its power from rectified utility AC power. In this mode, the rectifier also provides charging power to the battery.
SBypass mode – Utility power directly supplies the critical load.
SBattery mode – The battery cabinet provides DC power, which maintains inverter operation. The battery supports the critical load.
The UPS continually monitors itself and the incoming utility power, and automatically switches between these modes as required, with no operator intervention. The sophisticated detection and switching logic inside the UPS ensures that operating mode changes are automatic and transparent to the critical load. The UPS changes operating modes in response to:
SA command is an intervention that is externally initiated by an operator or by some site action. A command causes the UPS to switch operating modes; it usually does not require any further action.
SA notice is a minor system event that may or may not require your attention.
SAn alarm is a system event that requires immediate operator intervention.
System events, horns, and indicators are described in Chapter 11, “Responding to
System Events.”
The following paragraphs describe the differences in UPS operating modes, using block diagrams to show the power flow during each mode of operation.
EATON Powerware® 9315 UPS |
