Powerware 9315 - Manual (Page 53)

UNDERSTANDING UPS OPERATION
EATON Powerware ® 9315 UPS (500–750 kVA) Installation and Operation Manual S 164201244 Rev E www.powerware.com 7-3
7.1.1 Normal Mode
In Normal mode, utility AC power is supplied to the rectifier. The rectifier supplies DC
power to the inverter, which then supplies the critical load with AC power. The
rectifier also provides charging power to the battery. The battery charge condition is
monitored by the UPS and reported by a status indicator on the control panel. The
message System Normal appears in the status area of the control panel LCD
screen.
Figure 7‐2 shows the path of electrical power through the UPS system when the UPS
is operating in Normal mode.
FBP
Input
Transformer
Path of Electrical Power
Battery
Inverter Rectifier
DC
Link
CB2
(closed)
Output
Transformer
(closed)
CB3
(closed)
CB1
Rectifier
Input
Bypass
Input
(closed)
Output
Static Switch
(open)
CB4
Bypass
Figure 7‐2. Path of Current Through the UPS in Normal Mode
If the utility AC power is interrupted or is out of specification, the UPS automatically
switches to Battery mode to support the critical load with no interruption. When utility
power returns, the UPS returns to Normal mode.
If the UPS becomes overloaded or unavailable, the UPS switches to Bypass mode.
The UPS automatically returns to Normal mode when the error 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.