(I) Electrical component of 1.5 induction melting furnace:
Electrical parts include: power transformer, combined control cabinet (including isolation and power control cabinet), solid power supply (including filter reactor and compensation capacitor bank) and so on.
1.Rectifier transformers
1000KW Special rectifier transformer for power supply，Oil-immersed self-cooled all-copper wire ladle. In this set of equipment, the transformer model is ZS11-1500/10/2*0.8KV. The primary voltage of transformer is 10 kV and the secondary voltage is 2 V 750 V + 12 pulse 6 phase output. The short circuit impedance of the transformer ranges from 6% to 8%. A no-load manual voltage regulator is installed on the high voltage side of the transformer. The output voltage can be adjusted in -5%，0，+5% third shift.
2.Combined control cabinet
1) isolated switchgear
The isolated switchgear is connected between the power transformer and the intermediate frequency induction power supply. It is mainly used for isolating and repairing intermediate frequency power supply. The isolating switchgear is equipped with a large capacity isolating switch.
2) Power control cabinet
The main function of power control cabinet is to control the work of hydraulic oil pump, cooling pump and spare power motor or generator in electric furnace system.
Solid power supply model KGPS-1500-0.5S. This is a large-scale integrated circuit control solid-state power supply, using SCR frequency conversion, by the latest control board control. When working, the voltage, current, power, frequency and other technical parameters of the solid power supply, all automatic control. (figure below)
1) main circuit characteristics of solid state power supply:
(1) Integrated silicon controlled assemblies installed
SCR uses the latest stacked radiator assemblies, as shown below. This installation method makes the assembly and disassembly of SCR more convenient and scientific, and the circuit is more neat. When the silicon control is replaced, any silicon controlled element in the assembly can be replaced by loosing a top tightening bolt. The radiator assembly has a scale for fastening as a reference to ensure the correct compression force between SCR and radiator. Moreover, this installation method can reduce the volume of SCR assembly and increase the operation space in the gas cabinet.
（2）Large capacity filter reactor
Filtered reactors are very important for solid power supplies and have two functions. First, the output current of the rectifier is made smooth and stable. Second, when the inverter thyristor is short-circuited, the growth rate of the short-circuit current and the maximum short-circuit current are limited. If the parameter design of the filter reactor is unreasonable, the core material is not good or the manufacturing process is not good, which will have a great impact on the reliability of the solid power supply.
In order to ensure the reasonable parameters of the filter reactor, the filter reactor design software package was specially developed. The software design, especially considering the working environment of the filter reactor under the parallel inverter condition, and based on our experience in producing solid power for more than ten years. And compiled. It can fully optimize the parameters of the filter reactor. In particular, it can analyze the parameter variation of the filter reactor in the current range from 0 to 3 times the rated current, ensuring that the core will not pass when the current of the filter reactor is 3 times the rated current. Magnetic saturation. Because, when the solid power inverter thyristor is short-circuited, the current through the filter reactor is much larger than the rated current. At this time, if the core of the filter reactor is magnetically saturated, the filter reactor will lose the current limiting effect. Therefore, it must be ensured that the filter reactor core is not magnetically saturated when the current is greater than the rated current. Only in this way, the filter reactor has a good current limiting effect, ensuring that the maximum short-circuit current is limited to a reasonable range.
The silicon steel sheet of the filter reactor is a cold-rolled high-permeability product, the copper tube is a T2 extruded copper tube, and is wrapped with a high-strength mica tape, and the H-class insulation.
In order to reduce the working noise of the filter reactor, the silicon steel sheet adopts a special fastening process, and a special absorbent material is also filled between the silicon steel sheet and the air gap.。
output circuit of double voltage
In order to reduce the loss on the intermediate frequency transmission line, the compensation capacitor of the inverter is connected in series and parallel voltage doubler mode (as shown in the left figure). This connection allows the voltage on the electric furnace to be doubled compared to the inverter output voltage. Thus, at the same output power, the output current becomes 50% of the original, thereby reducing the loss on the intermediate frequency transmission line to 1/4.
