| 摘要 |
<p>1, 209,133. Automatic control systems for furnaces. ELEKTROKEMISK A/S. Feb. 10, 1969 [Feb. 10, 1968], No. 6992/69. Heading G3R. Electrodes 1, 2, in a smelting furnace are connected in series with each other through the scondary winding of a transformer 3. A balance relay 4 has one coil supplied from current transformer 5, and another coil connected either to the secondary winding of the transformer 3 or to a constant voltage source. Coils H1, H2, are adapted to control movement of the electrodes 1, 2, respectively, the right-hand part of each coil being energized for lowering the associated electrode, whilst the left-hand part is used for raising. A differential relay 9 has voltage coils each connected between its associated electrode and the furnace bottom, this relay transmitting impulses from relay 4 to coils H1, H2, in accordance with the positions of a pair of movable contact arms. If the current detected by the transformer 5 increases, an impulse for raising both electrodes is transmitted to the coils H1, H2, provided that the difference between voltages e1 e2, is within a prescribed limit. If the voltage el is substantially the greater, the impulse is transmitted to the coil H2 only. The system may be applied to a furnace equipped with six electrodes employing three single-phase transformers, or one three-phase transformer, each pair of electrodes being connected in series with one another to a D.C. power supply or a single phase of the A. C. supply. The relay 4 may be replaced by an electronic balance unit. The regulator may transmit pulses to the control circuit intermittently for fixed periods.</p> |
