Here are the standard types of power quality disturbances. For information on how to reduce these disturbances, see Power quality buffering equipment applications . Distortion can be caused by solid state devices such as rectifiers, adjustable speed controls, fluorescent lights, and even computers themselves. At high levels, distortion can cause computers to malfunctions and cause motors, transformers, and wires to heat up excessively.
Distortion is probably the most complicated and least understood of all power disturbances.
On large interconnected utility systems such as SRP's, frequency is very stable and deviations are rarely a problem. However, on smaller power systems, especially those supplied by on-site generators, frequency deviations can cause electronic equipment to malfunction and affect the speed of motor driven clocks. Transients Transients are sudden but significant deviations from normal voltage or current levels. Transients typically last from 200 millionths of a second to half a second. Transients are typically caused by lightning, electrostatic discharges, load switching or faulty wiring.