Users Manual Part 2

11.1.2.1
Backup Battery Charging Procedure
NOTICE: Selected Operation Mode: AC Operation
The backup battery charging output voltage is 40.5VDC to 57VDC and output current 0 to 6A.
A temperature sensor monitors the backup battery temperature to ensure optimum charging.
Available charge current is reduced linearly with increasing temperature from 6A to 0A when the PSU
input air temperature increases from +30 °C to +60 °C
Charge voltage decreases with increasing battery temperature with the ratio of -72mV/C, starting with
56.88VDC +/-1% at -10 °C and ending with 52.56 VDC +/-1% at +50 °C
The PSU charges the backup batteries on the following conditions (DC In Status LED is flashing fast
(0.5 s) red-green):
• Temperature range*:-10 °C to +50 °C
• Battery Low Voltage start up:40V -5%/+1%
• Battery Low Voltage Warning:43V ±2%
The PSU stops charging the backup battery on the following conditions:
•
Internal PSU temperature:> 100 °C
• Battery Temperature*: -12.5 °C
• Battery Temperature*:> 53 °C
*When a temperature sensor is connected to the battery and PSU. If the battery sensor is not
connected the battery will be charged with 54.24 ±1%VDC as if the battery temperature was 25 °C.
The battery temperature monitored through CAN Bus will show 100 °C.
11.1.3
Fans
The PSU supplies fans, which are located in the fan trays under the module cage. For more
information on fans, see Cooling Fans on page 367. The PSU DC output voltage dedicated for fans is
12 to 24VDC and the output current is 1 A for each fan.
Three fan output connectors supply three fan trays with two fans connected in parallel in each fan tray.
Fan supply output voltage can be automatically regulated as a function of PSU internal (ambient)
temperature and its output power. Fan supply output voltage can also be controlled by the CAN Bus in
7 steps from 24V to 12V. The highest value wins – automatic control versus CAN control.
At an ambient temperature below -10 °C the fans are stopped and restarted again at -8 °C. The fan
supply ramps up to 24V output for a few seconds in all start up situations.
11.2
Power Supply Unit (PSU) Indicators, Switches, and Connectors
The following figure shows the positions of indicators, switches and connectors on the PSU front panel.
6802800U74-AP
Chapter 11: Power Supply Unit
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