Surge Suppressor
Another problem with power is its “cleanness.” Although most people are unaware of it, a variation of 10 percent from the stated voltage of a line is considered acceptable, and some power lines vary even more. A particular power line may consistently be up to 10 percent high or low.
In many places, lights dim momentarily when a large appliance, such as an air conditioner, begins operation. When a large motor starts, it draws an exceptionally large amount of current, which reduces the flow to other devices on the line. When a motor stops, the sudden termination of draw can send a temporary surge along the line. Similarly, lightning strikes may send a momentary large pulse. Thus, instead of being constant, the power delivered along any electric line shows many brief fluctuations, called drops, spikes, and surges. A drop is a momentary reduction in voltage, and a spike or surge is a rise. For computing equipment, a drop is less serious than a surge. Most electrical equipment is tolerant of rather large fluctuations of current.
These variations can be destructive to sensitive electronic equipment, however. Simple devices called “surge suppressors” filter spikes from an electric line, blocking fluctuations that would affect computers. These devices cost from $20 to $100; they should be installed on every computer, printer, or other connected component. More sensitive models are typically used on larger systems.
