Electrical Power

Electrical power is something most of us take for granted, but large portions of the world live without dependable electrical power. Even in areas are subject to line noise or might suffer from electromagnetic interference (EMI). Electrical motors and other electronic devices can cause EMI. You might have noticed that florescent lights can also cause electrical problems; this phenomenon is known as radio frequency interference (RFI). Table 2.3 lists some other power anomalies.

Table 2.3. Power Faults and Descriptions




Prolonged loss of power


Power degradation that is low and less than normal


Momentary low voltage


Momentary loss of power


Momentary high voltage


Prolonged high voltage


Interference superimposed onto the power line


Noise disturbances of a short duration


Initial surge of power at startup

Luckily, power conditioners, surge protectors, and uninterruptible power supplies can provide the clean power needed to keep business going.

Uninterruptible Power Supply (UPS)

Since computers have become an essential piece of technology, downtime of any significant length of time can be devastating to an organization. Power outages can happen, and businesses must be prepared to deal with the situation. Uninterruptible power supplies are one of the primary means of meeting this challenge. Two categories of UPS exist:

  • Online system An online system uses AC power to charge a bank of DC batteries. These batteries are held in reserve until power fails. At that time, a power inverter converts the DC voltage back to AC for the computer systems to use. These systems are good for short-term power outages.
  • Standby system This type of system monitors the power line for a failure. When a failure is sensed, backup power is switched on. This system relies on generators or power subsystems to keep computers running for longer power outages.

The CISSP Cram Sheet

A Note from Series Editor Ed Tittel

About the Author


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The CISSP Certification Exam

Physical Security

Security-Management Practices

Access-Control Systems and Methodology

System Architecture and Models

Telecommunications and Network Security

Applications and Systems-Development Security

Operations Security

Business Continuity Planning

Law, Investigations, and Ethics


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CISSP Exam Cram 2
CISSP Exam Cram 2
ISBN: 078973446X
EAN: 2147483647
Year: 2003
Pages: 204
Authors: Michael Gregg

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