APC 9000 User Manual

34006452EN/AC

 - Page 11

Introduction

Operation with Mains 1 restored 

(figure 13) 

  

When Mains 1 power is restored or its voltage returns to within specified tolerances, the system automatically returns to its 
normal operating mode described above (on the condition it did not reach the end of battery power). 

If the end of battery power was reached (with the resulting inverter shutdown), the RC restarts automatically, but the inverter 

must be restarted manually, either locally or remotely in systems equipped with a remote-control unit.
The rectifier-charger recharges the battery which was discharged during the Mains outage.

In frequency converters without battery power, the return of Mains 1 power results in the automatic restart of the RC and the 

inverter.

The battery charge cycle takes place in two steps (see figure 14):

– step 1: the battery is recharged at a constant current limited to 0.1C10 (i.e. 1/10th of the battery capacity specified 
for a 10 hour discharge). The DC voltage increases with the battery charge until the charge level is reached;

– step 2: the battery is recharged at constant voltage equal to the charge level (maximum value 463 V). 

The charging current gradually decreases until reaching a specified low value (floating current).
For vented lead-acid batteries, the rectifier-charger supplies the charging voltage for 0 to 255 hours (parameter defined by 

the after-sales support department) and then the floating voltage. For sealed lead-acid batteries, the charging and floating 

voltages are the same.

Note: 
If the Mains 1 failure is shorter than 0 to 255 seconds (parameter defined by the after-sales support department), the charger 

does not initiate a complete charge cycle but automatically supplies the floating voltage.

mains 1

rectifier-

charger

battery

inverter

load

static switch

mains 2

current

limiting

0.1 C10

constant voltage

decreasing current

U charge/floating

(sealed batteries)

U "floating"

(vented batteries)