IV432E Rev.01 SIEL S.p.A.
Installation and user manual
Date of issue: 2021-05-05
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Operation
4.1 Operation Modes
The UPS is a double-conversion on-line UPS that may operate in the following alternative
modes
ƹ
Normal mode
The rectifier/charger derives power from the AC Mains and supplies DC power to the inverter
while floating and boosting charge the battery simultaneously. Then, the inverter converts the DC
power to AC and supplies to the load.
ƹ
Battery mode (Stored Energy Mode)
If the AC mains input power fails, the inverter, which obtains power from the battery, supplies the
critical AC load. There is no power interruption to the critical load. The UPS will automatically return to
Normal Mode when AC recovers.
ƹ
Bypass mode
If the inverter is out of order, or if overload occurs, the static transfer switch will be activated to
transfer the load from the inverter supply to bypass supply without interruption to the critical load. In
the event that the inverter output is not synchronized with the bypass AC source, the static switch will
perform a transfer of the load from the inverter to the bypass with power interruption to the critical AC
load. This is to avoid paralleling of unsynchronized AC sources. This interruption is programmable but
typically set to be less than an electrical cycle e.g. less than 15ms (50Hz) or less than 13.33ms (60Hz).
