Powerware 100160 kVA manual Path of Current Through the UPS in Normal Mode RT

Understanding UPS Operation

7.2.2 Normal Mode – RT

Figure 7-2 shows the path of electrical power through the UPS system when the UPS is operating in Normal mode.

K5

Static

Switch

Rectifier

K1

Battery

Converter

Breakers Contactors
Closed	Battery
	Breaker

Open

Battery

Inverter

K3

Main Power Flow

Trickle Current

Energized

De-Energized

Figure 7-2. Path of Current Through the UPS in Normal Mode – RT

During normal UPS operation, power for the system is derived from a utility input source through the rectifier input contactor K1. The front panel displays “Normal,” indicating the incoming power is within voltage and frequency acceptance windows. Three-phase AC input power is converted to DC using IGBT devices to produce a regulated DC voltage to the inverter. The battery is charged directly from the regulated rectifier output through a buck or boost DC converter, depending on whether the system is 208V or 480V and the size of the battery string attached to the unit.

The battery converter derives its input from the regulated DC output of the rectifier and provides either a boosted or bucked regulated DC voltage charge current to the battery. The UPS monitors the battery charge condition and reports the status on the control panel. The battery is always connected to the UPS and ready to support the inverter should the utility input become unavailable.

7-4 EATON Powerware® 9390 UPS (100–160 kVA) Installation and Operation Manual S 164201604 Rev B powerware.com