Characteristics of electric arc furnace transformer

Electric Arc Furnace Transformer

The electric arc furnace transformer is a Special transformer for supplying power to the electric arc furnace of iron and steel smelting. Large capacity, complex structure and high technical requirements. Its secondary side voltage is low, generally from tens of volts to hundreds of volts, and can be adjusted in a large range; The secondary current often reaches thousands to tens of thousands of amperes. In addition, in iron and steel smelting, the melting period requires large power, and the transformer is required to have 20% overload capacity within 2 hours. In the process of steelmaking, because the collapse of the furnace charge is easy to cause electrode short circuit, the primary side of the arc furnace transformer should be connected in series with a current-limiting reactor or have a large impedance to limit the short-circuit current.

When the electric furnace is running, it is also required that the power supply transformer can adjust the voltage. There are two ways to regulate the voltage of Electric Furnace Transformer.

1. Direct voltage regulation method: lead out Tap Changer on the original winding of transformer. △ - Y commutation can also be used between the three phases of the primary side to realize the secondary side voltage regulation. △ - Y switching is a very economical voltage regulation method. On the basis of not changing the number of turns on the primary side, the secondary side voltage can be reduced to 1/of the original. Because each phase winding has 9 taps, plus △ - Y commutation, a total of 2 can be obtained × 9 is level 18 voltage.

2. Indirect voltage regulation method: indirect voltage regulation method with series transformer. main transformer 1 is a three-winding transformer (see multi-winding transformer), and winding 1 is a high-voltage winding connected to the power grid; 2. The winding is a winding with tap, which is connected in series with the original winding 4 of the series transformer II through the tap changer; The 3 winding is connected in series with the secondary winding 5 of the series transformer II to supply power to the furnace load. By changing the primary voltage of series transformer II through tap changer, the output voltage of windings 3 and 5 can be changed. The 3 and 5 windings connected to the load generally have only 1 to 2 turns, and are usually made of copper or aluminum plate into an eight-shaped coil. Arc furnace transformer