Online Mode - Distributed Bypass; Figure 6-16. Path Of Current Through The Upss In Online Mode - Distributed Bypass - Eaton Power Xpert 9395 Installation And Operation Manual

Understanding UPS Operation
A command is an intervention that is externally initiated by an operator or by some site action. A command
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causes the UPSs 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.
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An alarm is a system event that requires immediate intervention.
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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.
Figure 6-16 shows the path of electrical power through the parallel system when operating in Online mode.
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 6-16. Path of Current through the UPSs in Online Mode - Distributed Bypass

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6-22 Eaton Power Xpert
Bypass Input UPS Input
Battery
Battery
Battery
Battery
Main Power Flow
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9395P-300 (300kVA, 300kW) UPS Installation and Operation Manual P-164000563—Rev 04 www.eaton.com/powerquality
UPS 1
UPS 2
UPS 3
UPS 4
Breakers
Closed
Open
Tie Cabinet
UPS 1 Output
UPS 2 Output
UPS 3 Output
UPS 4 Output
Output to
Critical Load