| 摘要 |
PROBLEM TO BE SOLVED: To provide an electric melting furnace capable of accurately grasping effective values of a voltage, an electric current and electric power, improving the controllability of an operation, increasing a degree of freedom in installation parts of switching elements in an electric circuit, reducing cost, and flexibly coping with individual demands by every plant. SOLUTION: A switch 47 switched to a-side only during a time when a switching element for a main electrode is in an ignition state, and outputting an instantaneous value of the voltage between the main electrodes 5 on the basis of information from an ignition state determining circuit 46 for the main electrode is disposed at the input side of a multiplier 19 to constitute a voltage effective value calculating circuit 18 for the main electrode, and a switch 49 switched to a-side only during a time when a switching element for a bottom electrode is in an ignition state and outputting an instantaneous value of the voltage between the bottom electrode 6 and one of the main electrodes 5 on the basis of the information from the ignition state determining circuit 48 for the bottom electrode is disposed at the input side of a multiplier 24 to constitute a voltage effective value calculating circuit 23 for the bottom electrode. COPYRIGHT: (C)2009,JPO&INPIT
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