| 摘要 |
1,067,335. Arc furnace control. ALLEGHENY LUDLUM STEEL CORPORATION. Sept. 2, 1965 [Sept. 15, 1964], No. 37619/65. Heading H5H. [Also in Division G3] A consumable electrode arc furnace, has means for sensing arc current and voltage which in the absence of both quantities for example on failure of the supply, causes the electrodes to move away from the melt a determined amount. When, after starting, the arc has reached stable conditions, a relay SA is energized through a manual switch 104. On cessation of the supply, voltage and current sensing relays VS, CS are de-energized, energizing relays V, C, hence lines 98, 100 are shunted through contacts C-3, V-4, SA-4, TD-1, thus energizing a raise circuit 96. A time delay relay TD is de-energized at the same time through contacts C-1, V-2, opening contacts TD-1 after an interval thus removing the shunt from lines 98, 100. The furnace may be alternatively controlled by an arc voltage circuit 52, 54 or a voltage discontinuity circuit 88, 90, 92 which causes pulses from a generator 57 to move the electrodes through a positional control arrangement in an approaching direction only. |
