3.3 OPERATING STATUS
The UPS has five different operating modes, as described below:
Normal operation
Green Conversion
Bypass operation
Battery operation
Manual bypass
3.3.1 Normal operation
During normal operation all the circuit breakers/isolators are closed, except for MBCB
(maintenance bypass).
The rectifier is supplied by the AC three-phase input voltage which, on its turn, feeds the inverter
and compensates mains voltage as well as load variations, keeping the DC voltage constant. At the
same time, it provides to charge the battery. The inverter converts the DC voltage into an AC sine-
wave with stabilized voltage and frequency, and also supplies the load via its static switch SSI.
Picture 2 – Normal operation
3.3.2 Green Conversion
During the operation in Green Conversion mode the battery is disconnected from the DC bus by
means of a static switch (see picture) and the rectifier works at reduced DC voltage; a control
algorithm provides to periodically re-connect the battery for recharge purposes (intermittent
charging).
Picture 3 – Green Conversion
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