Powerware 9335 User Manual download pdf (Page 33)

Powerware 9335 (80 kVA and120 kVA) Installation and Operation 5-3

164201396 REV. A 071103

5.2 Normal, Battery and Bypass Modes

The UPS system functions automatically to supply AC electrical power to the critical load.

There are four standard operation modes.

•

In Normal mode, the critical load is supplied by the inverter, which derives its

power from rectified utility AC power. In this mode, the battery charger also

provides charging current for the battery, if needed.

• In Battery mode, the critical load is supplied by the inverter which derives its

power from the battery DC power.

•

In Bypass mode, the critical load is directly supported by utility power via the

static switch. In this mode, the critical load is not protected.

•

In Maintenance Bypass mode, the critical load is directly supported by utility

power, but the UPS can be shut down for maintenance. The operator switching

the Maintenance Bypass Switch to the Bypass position accomplishes this,

however, the critical load is not protected.

The UPS continually monitors itself and the incoming utility power, and automatically

switches between these modes as required, with no operator intervention, except for the

Maintenance Bypass mode. The sophisticated detection and switching logic inside the

UPS ensures that operating mode changes are automatic and transparent to the critical

load.

System events are alarms and notices that are displayed on the LCD monitor panel.

They may or may not require operator intervention. See Chapter 9.

The following descriptions provide the differences in UPS operating modes.

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Powerware 9335 User Manual Page 33