What is power quality?
Power quality is a common term used to describe the performance of electrical power systems. With a good power quality, the systems function correctly without considerable loss of performance or life time. A power quality disturbance means that there is a change in power (voltage, current, or frequency), that troubles the normal operation of an electrical system.
The form in which electric power is delivered to consumers and businesses, is AC. Ideally, AC power can be seen as a smooth, symmetrical sine wave at 50 cycles every second, or in some parts of the world at 60 cycles every second. Any variation could be an indication of trouble.