Power factor correction and harmonic mitigation in a thyristor controlled glass melter

Operation of a new all-electric glass melting furnace in a manufacturing plant caused severe disturbances to other plant functions. The problem was traced to the thyristor controllers, which regulated power to melter electrodes. Investigation showed severe distortion of the plant feeder voltage waveform due to harmonic currents. Corrective measures consisted of installing a set of series resonant harmonic traps and a high-pass filter on the 4160 V feeder. Harmonic distortion of the supply voltage was reduced from 5% to less than 1%, and the power factor was improved. Normal plant operations were resumed.>