Delta Modulon DPH series, User Manual

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3 - 11
3 Operation Modes
3.1.11 Bypass Mode_ Single Input_ Parallel Units
In Bypass mode (parallel), when all inverters encounter abnormal situations such as
overload, short circuit, abnormal output voltage or low battery, they will automatically shut
themselves down. Meanwhile, if all parallel UPSs detect the bypass AC source is normal,
they will automatically switch to Bypass mode to protect the connected critical loads from
power interruption. The critical loads will be equally shared by all parallel units. After the
abnormalities mentioned above are eliminated, the parallel UPSs will switch back to On-
Line mode from Bypass mode. During Bypass mode (parallel), each UPS’s tri-color LED
illuminates yellow and each UPS’s LCD shows the text '
Bypass ' in the upper right corner.
Please refer to Figure 3-11 for the path of electrical power through the parallel UPSs in
Bypass mode.
MAIN
LOAD
MAIN
1
2
Q1
Q2
Q4
Q3
Batteries
Rectifier Inverter
Static Switch
Q1
Q2
Q4
Q3
Batteries
Rectifier Inverter
Static Switch
Q5
Q5
(Figure 3-11: Bypass Mode Diagram_ Single Input Parallel Units)