CompTIA A+® Certification All-In-One For Dummies®, 2nd Edition

6.7. Working with UPS and Suppressors

Some people have such good and stable power that they take it for granted. This is not the reality for many of us, though, and we live with a variety of power issues such as these:

• Spikes: Spikes are sharp increases in line voltage caused by a problem with the power utility equipment, which may be traced back to faulty transformers or lightning strikes.

• Power surges: Similar to spikes, power surges are increases in line voltage that usually last longer than a spike.

• Noise: Noise is interference caused by items not directly connected to the power system. Power lines running near fluorescent lights or microwaves can have their AC sine waves altered or chopped, which affects devices receiving their power.

  Figure 6.3. An AC power adapter for a Toshiba laptop.

  

  What about DC adapters? DC adapters allow you to convert DC voltages to different DC voltages, changing the power characteristics, such as current, to allow 12V power from a vehicle to be used for computers and other equipment that do not use12V power directly. You may use these from time to time to power other devices. However, because the power requirements for most laptops are high, you might not be able to use a 12VDC adapter to provide it power.

• Blackout: A blackout is a total interruption in the line power. The ATX power supply specification has a minimum voltage hold-up time of 17 milliseconds ...