Jeumont Schneider Corporation

Claude Boisdon

A system for supply of direct current to at least two electrical loads having a common polarity, especially for power supply to an arc furnace with several electrodes or to plasma generators, comprises a set of load-controlled rectifiers (7) arranged in a Graetz bridge (A, B, C), in parallel upon a common alternating current power supply (5, 6). The half-bridges (A.sub.2, B.sub.2, C.sub.2) situated on the common-polarity side have a common dephasing control voltage, while the half-bridges (A.sub.1, B.sub.1, C.sub.1) situated on the other side are each controlled individually. This mechanism can be used in particular for power supply to arc furnaces or plasma torches.

System for supply of direct current to at least two electrical loads

The invention concerns a control apparatus for an arc furnace (1) comprising at least one electrode (2), and powered with direct current from an alternating current electric power source (4), through the intermediary of a controlled-rectifier converter (3). According to the invention, this apparatus includes a loop (24) for rapid control of the reactive energy drawn from the alternating current power source (4), and a circuit (15) for limitation of the maximum intensity of the direct current flowing in the electrode (2). Preferably, the rapid control of the reactive energy is obtained by holding essentially constant the product of the intensity in the source (4) and the sine of the dephasing angle. It includes in addition a loop (13) for slow control generating a reference signal of the reactive energy applied to the said rapid control loop (24), and limiting the variation of the reactive energy.

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Avon, France

Claude Boisdon