Industrial power quality problems

Power quality has become an increasing concern to Alexandria Electricity Company (AEC) and has resulted in measuring power quality variations and characteristic disturbances for different industrial categories. Power quality disturbances are usually caused by load switching, system faults, motor starting, load variations, nonlinear loads, and intermittent loads and arc furnaces. These cause many electrical disturbances like surge, dip, harmonic distortions, interruptions, flicker and signaling voltages. AEC has already an extensive monitoring plan to help characterize system performance on a continuous basis. An important AEC quality problem service is the power disturbance log. This log is designed to help identify the causes of the equipment malfunction. The information in the log are date, time, list of equipment affected, length of outage and weather conditions. Accurate information provides valuable clues towards a solution. A log helps to systematically and quickly uncover important information. The paper presents analysis of the real time industrial electrical disturbances, power disturbance log and some suggestions to minimize or prevent inconveniences caused by power disturbances. The survey includes monitoring and analysis at the supply side and at 15 customer loads. The customers represent different industrial loads and are classified into metal, chemical, textile and food. By the use of protective devices some remedies are implemented against disturbances. Voltage profile before and after implementation is recorded.