Predicting the electrical performance of arc furnaces

Abstract

The paper develops a method of predicting the electrical performance of arc furnaces. The technique is based on a power chart derived from an equivalent phasor diagram. Comparisons with other methods of prediction and with practical observations are made. An approximate form of the operating chart is also presented which is applicable to systems having a low resistance/reactance ratio. List of principal symbols E a = level of arc voltage Vs,Va = r.m.s. values of supply voltage and fundamental component of arc voltagê 1, ^2, ^3 = instantaneous values of arc voltages V\,Vi,v 2 = instantaneous values of supply voltagesh,hth = instantaneous values of supply currents R = system resistance X = system reactance 0 = intrinsic phase difference between V s and V a 5 = system angle tan" 1 (R/X) p = radius of normalised operating circle S = apparent power P = power Q = reactive power subscript b refers to base values 1