14
30-200 kW
P-164000249
User's and Installation Guide
Revision 2
Internal relay contacts
Figure 2-4: Path of current through the UPS in double conversion mode
Three-phase AC input power is converted to DC using a multilevel converter with IGBT devices to
produce a regulated DC voltage to the inverter. The UPS status indicated on the display is “Unit
Online” and the UPM status is “Active”.
The battery converter derives its input from the regulated DC output of the rectifier and provides
regulated charge current to the battery. The battery is always connected to the UPS and ready to
support the inverter should the utility input become unavailable.
The inverter produces a three-phase AC output to the critical load. The inverter derives regulated
DC from the rectifier and uses multilevel converter technology with IGBT devices and pulse-width
modulation (PWM) to produce a regulated and filtered AC output.
If the utility AC power is interrupted or is out of specification, the UPS automatically switches to
Battery mode to support the critical load without interruption. When utility power returns, the UPS
returns to double conversion mode automatically.
If the UPS becomes overloaded or unavailable, the UPS seamlessly switches to Bypass mode and
continues supplying the load through the static bypass. The UPS automatically returns to double
conversion mode when the abnormal condition, such as an extended time overload, is cleared and
system operation is restored within specified limits.
If a UPM power module within the UPS suffers an internal failure, the remaining UPMs will continue
supporting the load in double conversion. The UPS is automatically internally redundant when the UPS
is not operating in full load. However, if there is no redundancy between the UPMs due to high load
level, the UPS switches automatically to Bypass mode and remains in that mode until the failure is
corrected and the UPS is back in service.
In an external parallel redundant system, each one UPS can be isolated from the system for service
while the remaining UPSs support the load in double conversion.
