HP Superdome SX2000 Generic Site Preparation Guide, Fourth Edition - Page 11

Electrical Load Requirements (Circuit Breaker Sizing), Power Quality, Sources of Voltage Fluctuations

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NOTE: Peripheral equipment should have dedicated breakers. Electrical Load Requirements (Circuit Breaker Sizing) IMPORTANT: Local authority has jurisdiction (LAHJ) must determine the final decision regarding adherence to country-specific electrical codes and guidelines. It is good practice to derate power distribution systems for the following reasons: • To avoid nuisance tripping from load shifts or power transients, do not run circuit protection devices continuously 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 HP servers operate over a wide range of voltages and frequencies. (See the HP Corporate Power Standard HP-00005-03 at http://standards.corp.hp.com/smc/hpstd/pdf/F-HP0000503.pdf.) The servers are tested and shown to comply with EMC Specification EN50082; however, damage can occur if these ranges are exceeded. Severe electrical disturbances can surpass the design specifications of the equipment. Sources of Voltage Fluctuations Voltage oscillations 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 Protect the server from the many sources 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 the effects of undesirable transmissions • Lightning arresters on power cables to protect equipment against electrical storms Precautions are 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. Adherence to the following guidelines provides the best possible performance of power distribution systems for HP computer equipment: • Dedicated power source-Isolates a server power distribution system from other circuits in the facility. • Missing-phase and low-voltage detectors-Shut equipment down automatically when a severe power disruption occurs. For peripheral equipment, these devices are recommended but optional. • Online UPS-Keeps input voltage to devices constant and should be considered if outages of one-half cycle or more are common. Electrical Factors 11

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NOTE:
Peripheral equipment should have dedicated breakers.
Electrical Load Requirements (Circuit Breaker Sizing)
IMPORTANT:
Local authority has jurisdiction (LAHJ) must determine the final decision regarding
adherence to country-specific electrical codes and guidelines.
It is good practice to derate power distribution systems for the following reasons:
•
To avoid nuisance tripping from load shifts or power transients, do not run circuit protection
devices continuously 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
HP servers operate over a wide range of voltages and frequencies. (See the HP Corporate Power
Standard HP-00005-03 at
.) The
servers are tested and shown to comply with EMC Specification EN50082; however, damage can
occur if these ranges are exceeded. Severe electrical disturbances can surpass the design
specifications of the equipment.
Sources of Voltage Fluctuations
Voltage oscillations 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
Protect the server from the many sources 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 the effects of undesirable transmissions
•
Lightning arresters on power cables to protect equipment against electrical storms
Precautions are 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.
Adherence to the following guidelines provides the best possible performance of power
distribution systems for HP computer equipment:
•
Dedicated power source—Isolates a server power distribution system from other circuits in
the facility.
•
Missing-phase and low-voltage detectors—Shut equipment down automatically when a
severe power disruption occurs. For peripheral equipment, these devices are recommended
but optional.
•
Online UPS—Keeps input voltage to devices constant and should be considered if outages
of one-half cycle or more are common.
Electrical Factors
11