What kind of intermediate frequency power supply can meet the requirements of induction melting furnace?

1 The output power requirements of the induction melting furnace for the thyristor intermediate frequency power supply.

The output power of the thyristor intermediate frequency power supply must meet the maximum power of the induction melting furnace, and the output power can be easily adjusted. This is because the life of the crucible of the induction melting furnace is usually about tens of furnaces and it is damaged. The crucible furnace lining must be rebuilt, and after the new crucible furnace lining is built, a low-power oven must be performed on it.Usually, the furnace starts from 10-20% of the rated power, and then increases the power by 10% at regular intervals until the rated power power. Furthermore, in the furnace process, when the charge is melted, the composition of the charge must be tested. During the test, in order to prevent the charge from melting and boiling violently, the intermediate frequency power supply must reduce the output power to keep the charge warm. In view of the above situation, it is required that the thyristor intermediate frequency power supply can be easily adjusted from 10%-100% of the rated output power. The diathermic furnace used for forging does not have a baking process.

2 The output frequency requirements of the induction melting furnace for the thyristor intermediate frequency power supply.

The relationship between the electrical efficiency and frequency of an induction melting furnace is related. Starting from the electrical efficiency, the output frequency of the thyristor intermediate frequency power supply can be determined. For example, we call this frequency fo. The inductor is actually an inductive coil, and in order to compensate the reactive power of the coil, a capacitor is connected in parallel at both ends of the coil, which constitutes an LC oscillating circuit. When the output frequency f of the thyristor inverter is equal to the natural oscillation frequency fo of the induction melting furnace loop, then the power factor of the loop is equal to 1. The maximum power will be obtained in the induction melting furnace. It can be seen from the above that the natural oscillation frequency of the loop is related to the values ​​of L and C. Generally, the value of the compensation capacitor C is fixed, while the inductance L changes due to the change of the permeability coefficient of the furnace material. The permeability coefficient μ of cold furnace steel is very large, so the inductance L is large, and when the temperature of the steel is higher than the Curie point, the permeability coefficient μ=1 of the steel, so the inductance L decreases, so the induction melting furnace loop The natural oscillation frequency fo will change from low to high. In order to make the induction smelting furnace always get the maximum power during the smelting process, this requires that the output frequency f of the thyristor intermediate frequency power supply can change with the change of fo, and always keep the frequency automatic tracking.

3 Other requirements for thyristor intermediate frequency power supply.

This is because when the furnace charge is smelting, once the intermediate frequency power supply fails, the crucible will be damaged in severe cases. Therefore, the thyristor intermediate frequency power supply is required to work reliably, and it must also have the necessary voltage-limiting current-limiting protection, over-voltage and over-current protection, and water cut-off. Protection, and other automatic protection devices. In addition, it is required that the thyristor intermediate frequency power supply has a high start-up success rate, and the start-stop operation should be convenient.