| 摘要 |
<p>1,185,742. Control arrangements for plasma arc furnaces. QUALITATS- und EDELSTAHLKOMBINAT VEB. 18 April, 1967, No. 17763/67. Heading H2H. The burner electrode 3 of a plasma arc furnace is moved vertically by a conventional piston and cylinder pneumatic driving mechanism 7 controlled by a current or voltage sensitive device 6 connected between the supply 8 and the furnace load (electrode, arc and material), the starting and operating of the furnace comprising the following steps :- 1. Electromagnetically - operated inlet and outlet valves 16, 17 are respectively closed and opened to move the burner 3 downwards. 2. The arc forms when the burner reaches ignition level A. 3. When the arc voltage or current reaches a predetermined value, the device 6 respectively opens and closes the valves 16, 17 to stop the .burner and then move it upwards. 4. When a pin 12 on the driving mechanism engages an upper limit switch 10, the mechanism is stopped and mechanically locked to fix the burner at its working level B. A lower limit switch 11 prevents the burner from being lowered below a safety level, operation of the switch 11 actuating the device 6 which operates as in steps (3) and (4) above to return the burner to level B.</p> |
