Powerware 9395 UPS 10001100 kVA - Manuel (Page 107)

UNDERSTANDING UPS OPERATION
EATON Powerware ® 9395 UPS (1000–1100 kVA) Installation and Operation Manual S 164201764 Rev 1 www.powerware.com 6−3
Static
Switch
Rectifier Inverter
K1 K3
Battery
Converter
Battery
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De−Energized
Closed
Open
Breakers Contactors
Static
Switch
K5
Rectifier Inverter
K1 K3
Battery
Breaker
Main Power Flow
Trickle Current
Energized
De−Energized
Closed
Open
Breakers Contactors
K2
Bypass Input
Rectifier
Input
Output
Bypass
Breaker
(CB4)
Input
Breaker
(CB1
Figure 6-2. Path of Current Through the UPS in Normal Mode
If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode.
The UPS automatically returns to Normal mode when the overload condition is
cleared and system operation is restored within specified limits.
If the UPS suffers an internal failure, it switches automatically to Bypass mode and
remains in that mode until the failure is corrected and the UPS is back in service.
6.2.3 Bypass Mode
The UPS automatically switches to Bypass mode if it detects an overload, load fault,
or internal failure. The UPS can also be transfered from Normal mode to Bypass mode
manually. The bypass source supplies the commercial AC power to the load directly.
Figure 6-3 shows the path of electrical power through the UPS system when
operating in Bypass mode.
C A U T I O N
The critical load is not protected while the UPS is in Bypass mode.
In Bypass mode, the output of the system is provided with three−phase AC power
directly from the system input. While in this mode, the output of the system is not
protected from voltage or frequency fluctuations or power outages from the source.
Some power line filtering and spike protection is provided to the load but no active
power conditioning or battery support is available to the output of the system in the
Bypass mode of operation.