| 摘要 |
<p>825,234. Automatic control systems for arc furnaces. BRITISH THOMSON-HOUSTON CO. Ltd. Dec. 2, 1957 [Dec. 3, 1956], No. 36931/56. Class 38 (4). Each electrode 3 of an A.C. arc furnace has its position controlled by a motor 10 so that the power taken by the arc is maintained substantially constant. The arc voltage is rectified at 6 and appears across R1, and a voltage proportional to arc current is obtained by current transformer 4 and rectifier 5 and appears across R2; these voltages are added and balanced against a reference voltage from potentiometer R3 by the use of amplidyne 9 with control winding 8, which supplies the armature of reversible D.C. motor 10. Since the control system acts to maintain the sum of the voltages across R1 and R2 constant, the power will be held substantially constant, at least for small changes in the voltages, since they are normally approximately equal. Instead of the mechanical coupling 12 between motor and electrode, the motor may move the electrode hydraulically by means of a pump, or the error voltage may be used to operate electromechanically controlled valves in an hydraulic system moving the electrode. In a further modification, an electronic amplifier or a magnetic amplifier as described in Specification 761,071 may replace the amplidyne 9.</p> |
