In recent years, the rapid growth of nonlinear loads, such as power electronic control equipment and arc furnaces, is creating harmonics and voltage distortion problems in power networks. In this paper we will present a comparative study of different arc furnace models for harmonics and voltage distortion analysis. Six different models of arc furnace representation of time domain and frequency domain are used for the analysis. Analysis of harmonics of arc voltage and current and voltage distortion has been conducted using different arc furnace models. Arc furnace models are implemented in and tested on a prototype system. The results have demonstrated that the accuracy of the different arc furnace models for analysis of both harmonics and voltage fluctuation is different.