Figure 2-4. Path Of Current Through The Ups In Double Conversion Mode - Eaton 93PR Series User And Installation Manual

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 toBattery
Mode to support the critical load without interruption. When utility power returns, the UPSreturns 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.
25-75 kW
11 User's and Installation Guide