GE Industrial Solutions Galaxy Vector Rack Mounted Controller J85501M-1 - Manual (Page 37)

Galaxy Rack-Mounted Vector Controller J85501M-1
Issue 2 January 2008 Operation 3 - 9
use of external thermistors at the plant batteries to monitor cell
temperatures. Refer to the Installation section for more details on
wiring and configuring this feature.
Thermal Compensation lowers plant voltage from the FSP for
monitored battery temperatures which are above the ideal
temperature established during configuration as the Battery
Thermal Slope Nominal Temperature. Lowering the plant
voltage helps to keep the batteries at their optimum state of
charge while protecting them from thermal runaway. Thermal
runaway is a complex sealed battery phenomenon where, for a
number of reasons, one or more cells in a string are unable to
dissipate the internal heat generated by their charging current
and experience an increase in internal temperature. By lowering
the float voltage as cell temperature increases, the float current
is lowered to a point where this destructive behavior can be
avoided. If a cell failure is imminent and the cell temperature
continues to rise above the threshold configured for Battery
Thermal Step Temperature, the plant voltage drops in a single
step to a level which helps keep from overcharging and
damaging the remaining cells in the string. Refer to Figure 3-1
for a graphical view of Battery Thermal Compensation and the
relationship of its various set points.
Refer to the Alarm Descriptions section for the Battery Thermal
Alarm and Temperature Probe Failure Alarm.
The Vector can also increase plant voltage above the FSP for
colder environments. Again, this seeks to keep batteries in such
an environment at their optimum charge state. Since this feature
results in an increase in plant voltage, it is activated through a
second enable switch during configuration. Again, refer to
Figure 3-1.