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Powerware 9335 (80 kVA and120 kVA) Installation and Operation 5-9
164201396 REV. A 071103
While in battery mode, the UPS will enunciate an audible horn, indicate the status change
on the front panel display with the message “MAINS NOT OK”, and make an entry into the
alarm event history. As the battery discharges, the boost converter and inverter constantly
make small adjustments to ensure a steady output. The UPS will remain in this operating
mode until the input power to the rectifier is again within the specified voltage or frequency
acceptance window.
If the input power fails to return or is not within the acceptance parameters required for
normal operation, the battery will continue discharging until a DC voltage level is reached
where the inverter output can no longer support the connected loads. When this occurs, the
unit will issue another set of audible and visual alarms indicating “BATTERY IN
DISCHARGE”. Unless the rectifier has a valid input soon, the critical load will only be
supported for about 3 minutes before the output of the system shuts down completely.
When this occurs, the LCD display will show the message “BATTERY DISCHARGED”.
If at any time during the battery discharge, the input power becomes available again,
contactors K1 and K4 are closed and the rectifier will begin to supply DC current to the
boost converter and inverter. The battery SCRs will be switched off while the battery
charger is turned back on to begin recharging the battery. At this point, the unit returns to
normal operation.
The systems total operating time on battery will depend on many factors. Some factors that
affect battery support times are battery type and capacity, number of parallel strings,
environmental temperatures, age of the battery, and fluctuations in load demand during the
discharge. The greater the load, the less support time the battery will provide. Decrease
the load and the battery support time will generally increase.