HP rp3440 Site Preparation Guide, Fifth Edition - HP 9000 rp3410/rp3440 - Page 21

General Site Preparation Guidelines Electrical Factors 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 You can protect the HP 9000 rp3410 and HP 9000 rp3440 servers 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 a HP 9000 rp3410 or HP 9000 rp3440 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 Distribution Hardware This section describes wire selection and the types of raceways (electrical conduits) used in the distribution system. Wire Selection Use copper conductors instead of aluminum; aluminum's coefficient of expansion differs significantly from that of other metals used in power hardware. Because of this difference, aluminum conductors can cause connector hardware to work loose, overheat, and fail. Chapter 2 21