GE Industrial Solutions CPS6000-M2 - Manual (Page 126)

CPS6000-M2 Installation Guide H5694720
Issue 8 January 2008 126
After this feature has been enabled, the system waits for 12 hours to ensure the battery strings are
stable. A battery string is considered to be stable if the charging current is less than 3A. If a stable
battery string yields a difference measurement greater than 1.7V for over 12 continuous hours, a
Battery Voltage Imbalance alarm is generated.
When the alarm is issued, the Float Set-Point (fsp) and the Battery on Discharge (BoD) threshold
values are reduced by fsp/number of cells per string. Once the alarm has been cleared by the CLE
command, the plant reverts to its normal fsp; however, the BoD threshold is maintained at the
new threshold for up to four minutes before reverting back to the old threshold. This is done to
ensure the batteries have had enough time to charge up to the nominal fsp and to prevent any
spurious BoD alarm conditions.
This feature may be used by customers as part of their overall battery maintenance program in
determining the health of battery strings. A voltage imbalance of 1.7V between half-string
voltages may mean a shorted-cell somewhere in the string. A service person should be sent out to
the site and determine if the string should be replaced.
Battery Recharge Current Limit
The Battery Recharge Current Limit feature must be enabled from the front panel or other remote
access means. The battery recharge current limit feature enables the Millennium II controller to
limit the recharge current flowing into the batteries or battery section during the charge cycle. The
recharge current flowing into the battery section can be limited to any value between 10A and
1000A.
Note that this feature will not have any impact on the current being delivered to the load. Further,
there will be no effect on the discharge current flowing from the battery strings to the load during
an ac fail condition. The controller will maintain the recharge current within 10% of the set level.