| 摘要 |
<p>PURPOSE:To protect the hearth of an arc furnace and to reduce the time of melting by controlling arc electric power continuously in accordance with the movement of an electrode in such a way that the arc electric power is lower the near the electrde goes to the hearth and that the arc power is increased gradually as the electrode rises. CONSTITUTION:An electrode 2 is put in an arc furnace 1 which is not charged with scraps, and the electrode is brought into contact with the hearth. The contact signal 52 of the electrode with the hearth of a pressure detector 8, and the moving signal 51 of the electrode position of a motor revolution detector 7 are inputted to an electrode position counter 11, by which an electrode relative position signal 53 for zero point correction is obtained. The output of the signal 53 enters a drop power setter 12 which outputs a power drop setting signal 54 in the direction of dropping the arc power in accordance with the progression of melting to a power supply controller 9. The signal 53 also enters a comparator 13 where it is compared with a reference signal 55 for electrode relative positions, and the approaching of the leading end of the electrode 2 to the hearth is detected. When the melting progresses, the signal 53 increases to permit raising of the arc power. A set signal 50 for power raising is outputted with a power raising setter 15 to the controller 9.</p> |
