| 摘要 |
<p>PURPOSE: To control electric current with proper responds independently of arc resistance which fluctuates based on the arc generating situation by providing a specified function regarding an electric current controlling device for arc furnace having a prescribed system to melt scraps by generating arc discharge. CONSTITUTION: An electric current controlling device for an arc furnace is one composed of an arc furnace 1, a d.c. reactor 3, an electric power transformer 4, an ignition angle controlling apparatus 5 to control the ignition angle of the electric power transformer 4, a current detector 6, and a current adjusting apparatus 7 to give a set instruction to the ignition angle controlling apparatus 5 based on an electric current signal from the current detector 6 as a feedback signal and the current controlling device is to melt scraps 11 by generating arc discharge. In the device, a voltage detector 8 and a computer 9 to carry out multiplication and division are installed, the current adjusting apparatus 7 is provided with an integration time changeable means for integration operation, and thus the current controlling device is provided with a function to compute a resistance value by the computer 9 based on the electric signals from the voltage detector 8 and the electric signals from the current detector 6 and to variably set the integration time by the integration time changeable means based on the value inversely proportional to the resistance value.</p> |
