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 through a DC to DC voltage converter. The battery charge condition is monitored by the UPS and reported by a status indicator on the Monitor Panel. The message “System Normal” appears in the status area of the LCD screen.

Figure 18 shows the path of electrical power through the UPS system when the UPS is operating in Normal mode.

 

 

 

 

 

Bypass

 

 

 

 

(BIB)

Input

 

 

 

 

 

 

 

 

 

(closed)

 

 

 

BYPASS

 

 

(MBP)

 

 

 

 

 

 

 

 

 

 

(open)

 

 

 

 

OUTPUT

 

 

 

 

 

TRANSFORMER

 

 

RECTIFIER

K4

INVERTER

 

 

 

 

 

Output

 

CB1

 

K3

 

Rectifier

 

(MIS)

 

 

 

 

 

Input

 

 

 

(closed)

 

 

 

 

(closed)

 

Input

Isolation

Transformer

DC/DC

CONVERTER

CB2

(closed)

BATTERY

Path of electrical power

Figure 18. 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 system becomes overloaded, 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.

Powerware BPIII Harsh Environment UPS 50--75 kVA Installation and Operation

41

164201261 Rev. F 111503

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Powerware 5075 kVA operation manual Path of Current Through the UPS in Normal Mode