Powerware (4080 KVA) 9390 User Manual download pdf (Page 70)

Understanding UPS Operation

7-16

Powerware

9390 UPS (40–80 kVA) Installation and Operation Manual S 164201535 Rev C

An ABM charging cycle starts with the charger driving the battery voltage, at maximum

current limit, to a battery c harge level of 2.34 volts/cell. The time it t akes for the voltage to

reach to the battery charge level is saved as the battery charge time. If the battery charge

time exceeds 100 hours, an alarm is annunciated.

As soon as a battery charge level of 2.34 volts/cell is reached, the battery is charged at a

float level of 2.31 volts/cell for 48 hours (battery float time) plus 150% of battery charge

time. Twenty-four hours into the float period, a series of battery tests are performed to

check the battery health. The float level charge continues after a successful test.

At initial startup, the battery run time on the front panel display indicates two minutes.

After the 24-hour float charging period and battery testing, the actual battery run time is

determined and the actual battery run time is displayed.

After the float period is completed, the charger is disconnected and the batteries are

allowed to rest for 672 hours (28 days) maximum rest time. If the battery voltage falls

below the opportunity charge level of 2.1 volts/cell during the first 240 hours of the rest

period, an alarm is annunciated.

An ABM charge cycle is initiated whenever one of these four conditions occurs since the

last charge cycle:

쑺 The batteries have rested over the maximum rest time of 672 hours.

쑺 Accumulated discharge time is over a maximum battery discharge time of 20 seconds.

쑺 Battery voltage is under the opportunity charge level of 2.1 volts/cell and the unit has

been in rest mode for longer than 240 hours.

쑺 An XCP command Initiate Battery Test is received.

7.4.4 Bypass

The bypass has a continuous-duty fully-rated SCR switch in the bypass circuit and a

contactor in the inverter leg. In Normal mode, the contactor connects the inverter to the

output. A backfeed contactor is also provided.

7.4.5 Batteries

The UPS operates from battery strings from 192 cells (384V nominal) to 240 cells

(480V nominal).

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Powerware (4080 KVA) 9390 User Manual Page 70