10.5 Power Issues
10.5.1 Identifying power issues
Blackouts, brownouts, noise, spikes, and surges are all examples of power interruptions that can cause system malfunctions or even complete system failure. These are explained in more detail below:
  • Blackouts – Blackouts are the complete loss of power for any amount of time. They are usually the result of a strong weather event such as high winds, lightning, or earthquakes. 
  • Brownouts/Sags – Sags and brownouts are a drop in power. A sag is a brownout that lasts less than a second. These incidents occur when voltage on the power line falls below 80 percent of the normal voltage. Overloaded circuits can cause them. Brownouts can also be caused intentionally by the utility companies seeking to reduce the power drawn by users during peak demand periods. Like surges, sags and brownouts account for a large proportion of the power problems that affect networks and the computing devices that are attached to them.
  • Noise – Noise is caused by interference from radio broadcasts, generators, and lightning. The ultimate effect is unclean power, which can cause errors in a computer system. 
  • Spikes Spikes are sudden increases in voltage that are much higher than normal levels. These are usually caused by lightning strikes but can also occur when the utility system comes back online after a blackout. 
  • Surges – A surge is a brief increase in voltage that is usually caused by high demands on the power grid in a local area. These can last for considerable amounts of time. When a computer receives too much power, it may cause the power supply to run hot or even stop working all together.
By having an understanding of the types of power issues that can cause problems with computer systems, preventing problems from occurring will be easier. The next section will discuss the different types of equipment that can be used to protect equipment from power events.