Changes in the Electrical Parameters during the Heat in an Electric Arc Furnace

Abstract

The character of changing the arc burning conditions is studied to consider the laws of changing the electrical parameters of a furnace, the arc length, and the conditions of melting and heating a metal during the heat both within each heat period and during transitions from one period to another. Within a heat period, the furnace parameters (power P_acos φ, R_F, HIC, arc length) are shown to increase continuously. During a transition to the next heat period, the parameters change jumpwise and then increase further within the period. The averaged parameters for each period are determined by the chosen transformer tap and the arc burning conditions. The influence of the heat time on the effect of a change in the furnace voltage on the main regime parameters, namely, the transmission coefficients based on voltage ($K_{U}^{P}$, $K_{U}^{{HIC}}$, $K_{U}^{{{{R}_{F}}}}$), has been studied. All K_U coefficients are shown to change from period to period and to increase during the heat. The average values of $K_{U}^{P}$ = $K_{U}^{{HIC}}$ over the periods are 1.5, 2, and 2.8, and those of $K_{U}^{{{{R}_{F}}}}$ are 2, 3, and 4.5. Within the periods, K_U decreases continuously with increasing period time. The peculiarities of the influence of the instability of the supply voltage (“interference”) on the heat parameters are considered. The difficulties related to the compensation of interference by switching transformer taps in the melting period at a decrease in the supply voltage and in the period of heating the liquid metal at its increase are considered.