"Power quality" refers to the steadiness of the electricity flow --- specifically the voltage --- that is generated, transmitted and delivered to an end-use customer. Disturbances on an electric line are frequently a concern for manufacturing facilities and the operation of medical equipment, servers, computers and other sensitive equipment, but they are a growing problem for residential customers, too. Power quality problems are solved by power conditioning.
Power Quality Problems
Power quality problems, or voltage fluctuations, are of three major types: surges, sags and spikes. A surge is an occurrence of too much voltage for 25 seconds or longer. A sag, sometimes called a "brownout," is an occurrence of less-than-normal voltage for 25 seconds or longer. A spike lasts only 2.5 seconds or less, but can carry several hundred volts. Surges and sags do not normally do a lot of damage. A spike, on the other hand, can destroy equipment or degrade it over the long term and cause it to fail prematurely.
Causes of Surges, Sags and Spikes
Surges can be caused when an appliance or piece of electrical equipment in a home or office cycles off or is turned off, resulting in "excess" available electricity for a short time. They are also caused when large electrical equipment on the same distribution line turns off. For example, when the refrigeration equipment at a convenience store cycles off, nearby homes may experience surges.
Sags can be caused by just the reverse: When large appliances or electrical equipment turn on, some electricity is temporarily diverted until the voltage adjusts.
Spikes are frequently caused by lightning strikes to cables, pipes or wires that travel into buildings and "blow out" anything electrical, such as light bulbs, sockets, microwaves, modems, hard drives or other computer-related equipment.
Purpose of Power Conditioners
Power conditioners deliver steady voltage without allowing irregularities in the power line to put sensitive load at risk. Power conditioners range from the simple and inexpensive to the complex and costly, depending on the economic or other consequences of electric disturbances, and are used by both small users and large industrial operations.
Types of Power Conditioners
Most households make use of one or maybe several surge protectors, also known as surge suppressors (pictured above). They are designed to control the voltage passing through to the devices plugged into them. Their lives are cut short, however, once they experience their first spike, e.g., from a lightning strike.
Electronic voltage regulators also maintain a steady electricity supply. There are many kinds of voltage regulators, depending on their application.
An uninterruptible power supply, or UPS, provides a constant flow of electricity in the event of sags or outages. It consists of a battery backup which will provide a seamless transition from AC power to battery-supplied power in the event of a loss of voltage.
Whole-house surge suppressors can be installed by your electric utility where electricity enters your home or business, that is, at your electric panel or on your meter.
Fuses and circuit breakers can react to too-high voltage under some circumstances.
Lightning arrestors can be used for larger electrical systems to divert lightning bolts into the ground.
Home and Office UPS Products
Several types and sizes of uninterrupted power supply systems are available for home and small businesses computers. They provide battery backup power in the event of sags and outages for a period of time (varies by model) to allow you to save your work and shut down your computer so valuable documents aren't lost.
Lowest-priced surge suppressors are not usually a bargain in the long run. The important consideration when shopping for a surge suppressor (or surge protector) is its joule rating and its clamping voltage. The joule rating is a measurement of how much energy the device can absorb, and the clamping voltage is the point at which excess voltage pass-through will be blocked.