HP 9000 rp5400 Servers - Manual (Page 144)

Power Consumption
When determining power requirements, you must consider any peripheral equipment that will
be installed during initial installation or as a later update. Refer to the applicable documentation
for such devices to determine the power required to support these devices.
Electrical Load Requirements (Circuit Breaker Sizing)
NOTE: Local authority has jurisdiction [LAHJ] and should make the final decision regarding
adherence to country- specific electrical codes and guidelines.
It is good practice to derate power distribution systems for one or more of the following reasons:
•
To avoid nuisance tripping from load shifts or power transients, circuit protection devices
should never be run above 80% of their root-mean-square (RMS) current ratings.
• Safety agencies derate most power connectors to 80% of their RMS current ratings.
Power Quality
The hp server is designed to operate over a wide range of voltages and frequencies. The server
is tested and shown to comply with EMC Specification EN50082. However, damage can occur
if these ranges are exceeded. Severe electrical disturbances can exceed the design specifications
of the equipment.
Sources of Voltage Fluctuations
Voltage fluctuations, sometimes called glitches, affect the quality of electrical power. Common
sources of these disturbances are:
•
Fluctuations occurring within the facility's distribution system
• Utility service low-voltage conditions (such as sags or brownouts)
• Wide and rapid variations in input voltage levels
• Wide and rapid variations in input power frequency
• Electrical storms
• Large inductive sources (such as motors and welders)
• Faults in the distribution system wiring (such as loose connections)
• Microwave, radar, radio, or cell phone transmissions
Power System Protection
The hp server can be protected from the sources of many of these electrical disturbances by using:
•
A dedicated power distribution system
• Power conditioning equipment
• Over- and under-voltage detection and protection circuits
• Screening to cancel out the effects of undesirable transmissions
• Lightning arresters on power cables to protect equipment against electrical storms
Precautions have been taken during power distribution system design to provide immunity to
power outages of less than one cycle. However, testing cannot conclusively rule out loss of
service. Therefore, adherence to the following guidelines provides the best possible performance
of power distribution systems for hp computer equipment:
•
Dedicated power source—Isolates an hp server power distribution system from other circuits
in the facility.
• Missing-phase and low-voltage detectors—Shuts equipment down automatically when a
severe power disruption occurs. For peripheral equipment, these devices are recommended
but optional.
• Online uninterruptible power supply (UPS)—Keeps input voltage to devices constant and
should be considered if outages of one-half cycle or more are common. Refer to qualified
contractors or consultants for each situation.
144 General Site Preparation Guidelines