Instruction manual

UNDERSTANDING UPS OPERATION
Eaton
®
9390 UPS (20–80 kVA) and 9390IT (20-40 kVA) Installation and Operation Manual S 164201603 Rev 4 www.eaton.com/powerquality
7-6
7.1.4 Energy Saver Mode – RT
When the UPS is operating in Energy Saver mode, the bypass source supplies the
commercial AC power to the load directly through the static switch. Some power line
filtering and spike protection is provided to the load but no active power conditioning
or battery support is available. All power converters are off and are in the ready state
(in case a forward transfer is needed). During this mode, the output contactor is
closed and the link is maintained through the diode bridge. Figure 7‐4 shows the path
of electrical power through the UPS system when operating in Energy Saver mode.
K5
Rectifier Inverter
K1 K3
Battery
Converter
Battery
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De-Energized
Closed
Open
Breakers Contactors
K5
Rectifier Inverter
K1 K3
Battery
Converter
Battery
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De-Energized
Closed
Open
Breakers Contactors
Static
Switch
Figure 7‐4. Path of Current through the UPS in Energy Saver Mode – RT
If the bypass source falls outside of a predetermined voltage or frequency window,
the system forward transfers to Battery mode and then to Normal mode with the
inverter assuming the load. The transfer takes place with a 2 ms typical transfer time,
to ensure loads being fed by the system output are not interrupted. All forward
transfers transfer to Battery mode before returning to Normal mode.
Energy Saver mode is a normal operating mode, and not an alarm condition. While the
UPS is in this mode, the NORMAL light on the front display will illuminate.