Electric arc furnace impact on generator torque

Electric arc furnaces draw power in pulses at approximately 5-6 Hz. This pulsing load is generally modeled as step-load-step-unload where the step is a complete load and complete unload. This step in power creates a step in the electrical torque of a generator supplying electricity to the electric arc furnace. This step in torque creates a torsional interaction that can be potentially damaging to interconnecting shafts and possibly other parts of the generator rotor train. In the worst case the generator would be completely loaded and completely unloaded during each pulse. This paper presents a description of a simple system that could be used to investigate this torsional response. PSCAD/EMTDC is used as the tool to perform this investigation. The simulation results and possible prescriptions are presented.