Power Quality

HP equipment is designed to operate over a wide range of voltages. However, damage can occur if this range is 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 fluctuations 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 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

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

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 server equipment:

Dedicated power source—Isolates server power distribution system from other circuits in the facility.
Low-voltage detector—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 are common. Refer to qualified contractors or consultants for each situation.

Power Quality

Technical documentation

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Sources of Voltage Fluctuations

Power System Protection