Superdome Servers - I/O Expansion Cabinet Guide, Fifth Edition

Appendix B
Site Requirements
Power Requirements
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• 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
This equipment can operate over a wide range of voltages and frequencies. It has been 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 Electrical Disturbances
Electrical disturbances, 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)
• Faults in the distribution system wiring (such as loose connections)
• Microwave, radar, or radio transmissions
Power System Protection
Computer systems 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
Adherence to the following guidelines provides the best possible performance of power distribution systems
for IOX equipment:
• Dedicated power source—Isolates 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 optional but recommended.
• Uninterruptible power supply (UPS)—Keeps input voltage constant and should be considered if outages
of one-half cycle or more are common. Refer to qualified contractors or consultants for each situation.
Distribution Hardware
This section describes wire selection and the types of raceways used in the distribution system.