The principle of induction melting furnace and the cause of capacitor damage
The principle of the induction melting furnace: the intermediate frequency current is generated in the inverter through the thyristor rectification and sent to the furnace body coil. The intermediate frequency electromagnetic field is generated in the furnace body (coil), so that the metal in the furnace body generates eddy current, and the eddy current generates a large amount of metal The heat energy melts the metal. The induction melting furnace is also a kind of induction furnace. The working process is as follows: firstly, the three-phase alternating current is rectified (using a thyristor) into a single-phase direct current through an inverter power supply, and then the inverter bridge is inverted into a 500-1000Hz intermediate frequency The pulse alternating current is then passed through the copper ring in the furnace to form a magnetic field. The magnetic field causes the steel in the ring to generate eddy currents. The eddy currents flow through the heated steel to generate heat, thereby achieving the purpose of smelting the steel. The general frequency of the induction melting furnace is 800-20000 Hz. If the capacitor of the induction melting furnace burns out, the main reasons are as follows:
1. The cathode of the electric heating capacitor is grounded. If the electric heating capacitor has poor insulation during the use of the electric furnace, the capacitor cathode will be grounded and the capacitor casing will break down. If this happens, the capacitor cabinet needs to be The insulation is reprocessed;
2. Lack of water. During the long-term use of the induction melting furnace, scale may form in the cooling pipe of the capacitor or the water inlet system may be blocked by debris, causing the electric heating capacitor to overheat and burn out. Therefore, pay attention to the flow of the cooling water of the electric heating capacitor during use. If the flow is abnormal, corresponding measures should be taken;
3. The intermediate frequency voltage is too high. During the long-term use of the induction melting furnace, if the induction melting furnace is adjusted too high, higher than the rated voltage of the electric heating capacitor (the rated voltage of the electric heating capacitor has 750V, 1200V and other common specifications), it will Resulting in overvoltage breakdown of the electric heating capacitor. If this happens, you need to lower the intermediate frequency voltage or replace the electric heating capacitor with a model with a higher voltage rating.
