| 摘要 |
The object exists for a device for supplying electrodes of a furnace via main transformers and additional transformers of achieving a low mains feedback effect, improved current stabilisation and, in the case of multi-electrode furnaces, also individual control of the real powers between the electrodes. This is achieved by the following means: a) the current in each phase of the secondary winding is measured, rectified and supplied as the actual current value to a summation point (25) in which the difference between the desired current value and the actual value is formed; the control deviation is supplied to a controller (29) whose output signal is supplied to a control-pulse transmitter (30) which produces suitable triggering pulses for a single-phase thyristor actuator (7), the thyristor actuator being connected in series with an intermediate-circuit winding (6') of the main transformer (3) and the associated primary winding (5') of the additional transformer (2); b) one changeover switch (10 or 11, 12 respectively) is provided per intermediate-circuit winding, by means of which changeover switch the additional voltage is added to or connected in opposition to the main voltage; c) the desired values for the current (-WiT2) and the voltage (-Xu) per electrode are specified for the summation points (25 and 46 respectively) in accordance with a furnace operation diagram. <IMAGE>
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