Introduction to Power Quality

Introduction to Power Quality

Introduction

^ü   Power quality is any abnormal behavior on a power system arising in the form of voltage or current, which affects the normal operation of electrical or electronic equipment.

^ü   Power quality is any deviation of the voltage or current waveform from its normal sinusoidal wave shape.

^ü   Power quality has been defined as the parameters of the voltage that affect the customer’s supersensitive equipment.

^ü   Power quality problems are

o  Voltage sag

o  Voltage swell

o  Voltage Flicker

o  Harmonics

o  Over voltage

o  Under voltage

o   Transients

^ü   Voltage sags are considered the most common power quality problem. These can be caused by the utility or by customer loads. When sourced from the utility, they are most commonly caused by faults on the distribution system. These sags will be from 3 to 30 cycles and can be single or three phase. Depending on the design of the distribution system, a ground fault on 1 phase can cause a simultaneous swell on another phase.

^ü   Power quality problems are related to grounding, ground bonds and neutral to ground voltages, ground loops, ground current or ground associated issues.

^ü   Harmonics are distortions in the AC waveform. These distortions are caused by loads on the electrical system that use the electrical power at a different frequency than the fundamental 50 or 60 Hz.