Dynamic Secondary Power Factor Correction for ac arc furnaces

Dynamic Secondary Power Factor Correction for ac arc furnaces is able to be combined with harmonic filtering and accomplish several highly valuable functions in power conditioning on the secondary furnace transformer sides.


The same is not possible by compensating on the furnace transformer primary sides.


The main advantages that are gained from a Dynamic Secondary Power Factor Correction scheme are:

  • Harmonic-free switching
  • Harmonic current filtering, which could include for 2nd, 3rd, 5th and others
  • Voltage regulation on a per-cycle basis
  • Phase balancing on a per cycle basis in the presence of furnace unbalance
  • Per cycle power factor correction
  • Stiffening of the supply network, enabling more power to be drawn from the utility
  • A reduction in the maximum power demand without compromising on the average power drawn by the furnace
  • Higher production throughput through the furnace at the same incoming power level
  • Increased arc stability
  • Reduced Voltage flicker
  • Drastic reduction in harmonics through the furnace transformer


Take note

  • Ac arc furnaces are notorious for contributing to power quality problems.
  • Now dynamic compensation at low voltage can now be used instead of static VAr compensation on the MV side.
  • Dynamic compensation removes the need for special harmonic filtering.


Published as:

Dynamic compensation for ac arc furnaces

By P Swart Mechanaut Systems and F Greyling, GLPS Project Management and

Engineering Systems

Electricity+Control, May 2012 (pgs 44 - 48)