6. Operating Overview
6.1 Operating Modes
Normal (Double Conversion, VFI)
Power flows through the UPS rectifier and inverter. Voltage and
frequency to the load is independent of voltage and frequency from the
input. There are higher efficiency losses in this mode due to the double
conversion process.
Q
2
Maintenance Breaker
STS
Bypass
Rectifier
Main
Q
1
Input Breaker
Battery Breaker
6.2 Single or Dual Feed Input
The UPS can accept dual inputs for additional redundancy (e.g. in a server rack installation operating on dual AC feeds).
When powering the UPS with dual AC feeds, first remove the jumpers, as shown below.
Small- and Medium-Frame Units
For dual input installation, red, yellow and black wire jumpers must be
removed as shown in Figure 6.3 (top rear view of cabinet).
Inverter
Inverter
Q
3
Relay
Output Breaker
Figure 6.1
INPUT 2
INPUT 1
Figure 6.3
ECO Mode
When utility power quality is stable, power can be diverted through the
automatic bypass of the UPS. If the utility power goes out of tolerance
or is lost, the UPS transfers quickly back to inverter to power the load
in VFI mode. The result is improved efficiency and cost savings when
power conditions are good.
Maintenance Breaker
Bypass
Rectifier
Load
Main
Q
1
Input Breaker
Large-Frame Units
INPUT 1
For dual input installation, busbar jumpers must be removed as shown
in Figure 6.4 (top view of cabinet).
12
Q
2
STS
Inverter
Inverter
Relay
Battery Breaker
Figure 6.2
BUSBAR
INPUT 2
Figure 6.4
Load
Q
3
Output Breaker