Understanding UPS Operation
6-24
Eaton
®
Power Xpert
®
9395P-900 UPS Installation and Operation Manual
P-164000501—Rev 09
www.eaton.com/powerquality
l
A
command
is an intervention that is externally initiated by an operator or by some site action. A command
causes the UPSs to switch operating modes; it usually does not require any further action.
l
A
notice
is a minor system event that may or may not require attention.
l
An
alarm
is a system event that requires immediate intervention.
The following paragraphs describe the differences in the parallel system operating modes, using block
diagrams to show the power flow during each mode of operation.
6.4.2
Online Mode - Distributed Bypass
In Online mode, utility AC power is supplied to the UPSs. Each UPS then conditions the incoming AC power
and provides clean, regulated AC power to tie cabinet or distribution panel for parallel systems up to four
modules. The applied load is shared equally among the available UPMs in the system.
If the utility AC power is interrupted or is out of specification, the UPSs automatically switch to Battery mode
to support the critical load without interruption. When utility power returns, the UPSs return to Normal mode.
If the UPSs become overloaded or unavailable, the distributed bypass system switches to Bypass mode. The
distributed bypass system automatically returns to Normal mode when the overload condition is cleared and
system operation is restored within specified limits.
Figure 6-18. Path of Current through the UPSs in Online Mode - Distributed Bypass
Main Power Flow
UPS 1
UPS 2
UPS 3
UPS 4
Output to
Critical Load
Battery
UPS Input
Tie Cabinet
UPS 1 Output
Bypass Input
UPS 2 Output
UPS 3 Output
UPS 4 Output
Battery
Battery
Battery
Closed
Open
Breakers
Summary of Contents for Power Xpert 9395P-900 Series
Page 2: ......
Page 8: ...This page intentionally left blank...
Page 33: ...Section I Installation...
Page 34: ......
Page 139: ...Section II Operation...
Page 140: ......
Page 231: ......
Page 232: ...P 164000501 6 P 164000501 9...