Analysis of power quality issue in arc furnace capacitor bank system

In large furnace industry in Thailand, power factor has become a concerned issue due to electric utility department that charges extra money from factory causing low power factor. Many factories have been using capacitor bank to compensate reactive power, thus, increasing power factor in factory. With the capacitor bank, power quality in terms of harmonic current has become problem due to the switching transient that magnifies current harmonics and causes severe damage to capacitor bank and other nearby sensitive equipment. This paper aims to study power quality issue in terms of harmonics in steel furnace factory and its effect when switching capacitor bank into system. The study is done by using data from furnace plant in Phetchaburi province, Thailand as case study. The result reveals that after switching capacitor bank, harmonics have been significantly increased, thus, protection scheme must be implemented to ensure safety and reliability of the plant.