CONTROL OF ELECTRIC POWER FOR DC ARC FURNACE

摘要

PURPOSE:To shorten smelting time by supplying the maximum electric power to a movable electrode when an arc is stabilized. CONSTITUTION:When a DC voltage is supplied to a movable electrode 5 and an arc Q is generated between the movable electrode 5 and scrap 6, the scrap 6 is smelted while the movable electrode 5 is descended gradually and enters into poling. In this case, a pulse generator 31 generates a pulse in accordance with the rotating number of a motor 8 for elevating the electrode. A poling speed detecting unit 32 counts the pulse signal at every predetermined sampling period to obtain the present position of the movable electrode 5. The poling speed detecting unit 32 operates the poling sped of the movable electrode 5 from a difference between the present position and a position detected at previous time and the sample period. A change of setting judging unit 33 changes the setting of a set voltage Vs and a set current Is to the maximum allowable values when a deceleration is detected as the result of comparison between the operated poling speed and a speed operated at previous time.