Bypass Mode_ Dual Input_ Parallel Units - Delta Modulon DPH Series User Manual

3.2.10 Bypass Mode_ Dual 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 see Figure 3-24 for the path of electrical power through the parallel UPSs in Bypass
mode.
1
BYPA.
MAIN
Batteries
2
BYPA.
MAIN
Batteries
(Figure 3-24: Bypass Mode Diagram_ Dual Input Parallel Units)
Modulon DPH Series
Q3
Static Switch
Q2
Rectifier
Q1
Q5
Q3
Static Switch
Q2
Rectifier
Q1
Q5
3-24
Inverter
Q4
Inverter
Q4
LOAD