Normal Mode - Parallel; Figure 7-5. Path Of Current Through The Upms In Normal Mode - Parallel - Eaton Powerware 9390 Installation And Operation Manual

7.2.2 Normal Mode – Parallel
In Normal mode, utility AC power is supplied to the UPMs. Each UPM then conditions
the incoming AC power and provides clean, regulated AC power to either a module
tie cabinet or distribution panel for parallel systems up to four modules. The applied
load is equally shared among the available UPMs in the system.
Figure 7‐5 shows the path of electrical power through the parallel system when
operating in Normal mode.
Bypass Input UPM Input
Battery
Battery
Battery
Battery
Main Power Flow
If the utility AC power is interrupted or is out of specification, the UPMs automatically
switch to Battery mode to support the critical load without interruption. When utility
power returns, the UPMs return to Normal mode.
If the UPMs become overloaded or unavailable, the parallel system switches to
Bypass mode. The parallel system automatically returns to Normal mode when the
overload condition is cleared and system operation is restored within specified limits.
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EATON Powerware 9390 UPS (20–80 kVA) Installation and Operation Manual
UPM 1
UPM 2
UPM 3
UPM 4
Breakers
Closed
Open
Figure 7‐5. Path of Current through the UPMs in Normal Mode – Parallel
UNDERSTANDING UPS OPERATION
Module Tie Cabinet
UPM 1 Output
UPM 2 Output
UPM 3 Output
UPM 4 Output
Output to
S
164201603 Rev 2 www.powerware.com
Critical
Load
7-9