To provide an electrode lifting/lowering device of an arc furnace for steel making capable of changing over a dead zone width to a proper value according to a status of the furnace, and improving efficiency in furnace operation and the adjustment of the dead zone width.
This electrode lifting/lowering device comprises an electrode 3 generating an arc between a scrap 2 and the furnace in a furnace body 1 and melting the scrap 2, an electrode lifting/lowering control board 6 for lifting and lowering the electrode 3 by controlling an electric motor 5, a comparing unit 7 outputting a corresponding speed command value to the electric motor 5 so that an actual current and an actual voltage supplied to the electrode 3 are agreed with set values, and a sensitivity dead zone characteristic generator 13 outputting the command value based on the prescribed dead zone characteristic curve or zero to the electrode lifting/lowering control board 6 on the basis of the speed command value outputted from the comparing unit 7. Furthermore, a dead zone automatic adjusting circuit 15 is disposed to adjust the dead zone width of the sensitivity dead zone characteristic generator 13, so that the dead zone width is automatically adjusted on the basis of a lapse time after the start of charging to the electrode 3.
COPYRIGHT: (C)2010,JPO&INPIT
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Hideki Takahashi