Service manual

System Overview 1-99
Figure 1–45 shows the 1600 watt 48V power supply. The power supply plugs
into the power subrack. To differentiate it and the 1000 watt 48V power supply
used in drawer systems, note the back plug receptacle shapes are different (
in
Figure 1–45 and
in Figure 1–50).
Features of the power supply are:
• 48 VDC and Vaux outputs. Vaux is always on when AC power is applied. 48 VDC
output is controlled by an enable signal provided by the PSMs in the system.
• Power factor correction on AC input
• May be placed in parallel
• May be hot swapped
• Dual speed fan – low speed when only Vaux is output, high speed when both
voltages are output
• Output is automatically adjusted to 48V by sensing voltages at the load and
changing power supply output accordingly
• Fault protection for:
− Overcurrent
− Overvoltage
− Overtemperature
• Status signals
− VAUX_OK_L
− 48V_OK_L
− PS_PRESENT_L
• LEDs
− Vaux is always on when AC is applied and within regulation
− 48V is on when the power supply is enabled and within regulation