U L T R A F L E X H D P D U U S E R M A N U A L
3.6
Grounding
3.6.1
PDU Facility
Ground Connection
The main AC input ground is located close to the input circuit breaker CB1. Refer to section 1.1.4 in the
service manual for details on connections to the AC ground.
3.6.2
PDU Frame ground
A frame ground connection is provided on the PDU near the main AC input. Refer to section 1.1.5 in the
service manual for details on connecting the frame ground.
3.6.3
DC Grounding
The 48V DC return is connected to chassis ground within the PDU. The connection is made between the
power supply output and chassis on the power supply backplane (PCB the power supplies plug into).
3.7
DC Distribution
The PDU provides a main 48V DC output as well as a 48V output for system fans. The 48V power supplies in
the PDU receive AC as soon as the main AC breaker (CB1) and power supply AC input breaker (CB9) are
turned on. The 48V output is inhibited (off) until commanded to turn on by the SMC controller. The 48V
output is inhibited (off) even if SMC is not present or is disconnected. While the power supplies are inhibited,
you may hear a “clicking” noise. This noise is normal and is a result of the magnetics in the power supply
operating in a no-load condition.
3.7.1
DC Ratings
below for the DC output ratings of the PDU. Refer to Fan Power section
below for
pinout details on the fan power connectors.
DC Output
Output connector Max
Current Max
Power
Main 48V Output
Bus bars
300 A
14,400 W
7.5 A (running)
360 W
Testhead Fans
J46
9.5 A (locked rotor)
456 W
1.75 A (running)
84 W
Cabinet Fan
J47
2.25 A (locked rotor)
108 W
1.75 A (running)
84W
Expansion cabinet fan
J48
2.25 A (locked rotor)
108 W
Expansion cabinet power
J49
-
15 W
Table 8 – DC Output Ratings
708401 Rev B
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