Understanding UPS Operation
The UPS continually monitors itself and the incoming utility power, and automatically switches between these modes as required, without operator intervention. The sophisticated detection and switching logic inside the UPS ensures that operating mode changes are automatic and transparent to the critical load, while internal monitoring systems indicate the current mode of operation. The UPS switches operating modes in response to these system events:
A 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.
A notice is a minor system event that may or may not require attention.
An alarm is a system event that requires immediate operator intervention.
System events, alarm horns, and indicator lights are described in Chapter 12, “Responding to System Events.”
The following paragraphs describe the differences in the three UPS operating modes, using block diagrams to show the power flow during each mode of operation.
EATON Powerware® 9390 UPS |
