Chapter 20 Power System: Description/Calculating Power Usage
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Power System

The modular power system for the server is provided by up to three autoranging power supplies
and a midplane. When connected to 100-120VAC mains each power supply is capable of
delivering 650 watts DC. When connected to 200-240VAC mains each power supply is capable of
delivering 750 watts DC. The power system may be configured with two power supplies (standard)
or three power supplies (2 + 1, redundant). The power supplies are mounted in a 2 + 1 pattern in
the back of the chassis along the bottom. Each power supply has an integrated fan for cooling.
The midplane provides connectors for the hot-swap power supplies. The midplane is the DC
power distribution hub providing connectors for the CPU baseboard, memory modules, I/O
baseboard, and peripheral bay. The midplane also provides the interface logic for power supply
related management functions.
Operator accessible areas are mechanically shielded from energy hazards while hot-swapping—
installing or removing—a hard disk drive, or a system fan. PCI hot-plug expansion boards are
240VA protected by current limiting circuitry on the PHP I/O board.
Care must be taken not to overload an AC mains circuit by plugging to many loads into a single
AC circuit. It is recommended to either plugging the power cord of the server in a separate circuit
or calculating the current drawn from loads attached to an AC circuit to make sure AC current
limits will not been exceeded.
If a power supply fails in the redundant power system, an LED marked “FAIL” at the back of the
power supply illuminates yellow. If a power supply predictive failure event occurs in the redundant
power system, an LED marked “PRFL” at the back of the power supply blinks yellow. In both
cases, the yellow power supply failure LED on the front panel starts flashing. The supply can be
hot-swapped—removed and replaced—without turning off the power or impacting server
operations. If the load on a single power supply exceeds the output ratings defined in Table 20-2,
an LED marked “FAIL” at the back of the power supply blinks yellow and the entire power system
is shut down.