An engineering evaluation of the 22kV systems of the Middelburg Ferrochrome plant with the aim to “quantify the harmonic voltage & current distortions and the unbalance levels resulting from operating the 22kV DC Arc furnace and the 22kV MTC’s Open Arc, Sub Arc C & B furnaces all supplied from the same 22kV Rockdale busbar “ was required. The starting point was to perform trended power measurements of the substations feeders/incomers which include voltage & current harmonics as well as positive, negative and zero sequence components of the voltages and currents (done by senior technician). The existing ETAP® MFC plant model was then used to simulate the total voltage harmonic distortion (VTHD) and harmonic impedance. The harmonic study portion was conducted by Das Venter whereas I performed the unbalance study portion. I then combined both reports to produce one report covering both studies.


  • Harmonic voltage and current distortion data analysis of the 22kV MTC PFC banks and the DC Arc furnaces & the 3rd & 5th C-Type harmonic filtering;
  • A simulation study representing the harmonic distortion in ETAP;
  • Voltage and current unbalance data analysis of the 22kV MTC furnaces;
  • Comparison of the measured harmonic distortion and voltage unbalance with the NRS-048 standard;
  • The recommended corrective action and its high level implementation;
  • Compiling a comprehensive technical report on the above analyses;
  • Power point presentation to the MFC personnel.