PURPOSE: To suppress variation of the electric power due to shortcircuit and stabilize the input power by setting three respond modes according to the operating conditions while the electric power is varying, and controlling the tap voltage and the set current.
CONSTITUTION: When there is no stability in the electric power, the present situation of the tap voltage set in a transformer and the furnace ceiling temp. are checked, and if a rise is admissible, the tap voltage set by a voltage setting device 7 is raised as the first respond mode. When the voltage is boosted, an electrode control device 5 gives a rise command to an electrode raising/sinking device 3 to cause elevation of the electrode 2. In case no rise of the voltage and temp. is admissible, the set current set in a current setting device 9 is put sinking as the second respond mode, and the device 3 elevates the electrode 2. When no enhancement of stability in the power is provided in the first respond mode while no stability is given in the second respond mode, the tap voltage is sunk as the third respond mode along with a sink of the set current and when an enhancement of the stability is discerned, a further sink is made, and attainment of sufficient stableness initiates returning of the current and voltage to their initial values.
GOTO HIROSHI
MORISADA KIYOTO
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