The induction furnace with frequency in the range of 150-10000 Hz is called an intermediate frequency furnace. The complete equipment of medium frequency induction furnace includes power supply and electrical control part, furnace body part, transmission device, and water cooling system.
The intermediate frequency furnace is especially suitable for large, medium and small furnaces with capacity of 10kg and dozens of tons, smelting steel, cast iron, copper, aluminum and other non-ferrous metals and their alloys and heat preservation of liquid metals. It has a strong adaptability to furnace burden and is suitable for intermittent operation. The furnace structure and use situation are similar to the power frequency coreless induction furnace. Since the 1970s, with the increasing power and reliability of high efficiency, static and metal saving thyristor medium frequency power supply, the medium frequency furnace has developed rapidly at home and abroad. It has obvious advantages not only in small and medium capacity but also in large capacity.
The IF intermediate frequency furnace cannot be started normally for the following reasons:
First, fault phenomenon when starting, the DC current is large, the DC voltage and the intermediate frequency voltage are low, and the equipment sounds dull and overcurrent protection. The thyristor with one bridge arm of the inverter bridge may be short-circuited or open circuit, causing the inverter bridge three-arm bridge to operate.
Second, the fault phenomenon when the DC current is large, the DC voltage is low, the intermediate frequency voltage can not be established normally, the compensation capacitor short-circuits disconnection capacitor uses a multimeter to find the short-circuit capacitor to replace the short-circuit capacitor.
Third, the failure phenomenon Heavy load cold furnace starts, the electrical parameters, and sound are normal, but the power does not rise, over-current protection analysis and processing.
- The inverse transform flow angle is too small. Use an oscilloscope to view the commutation angle of the inverter thyristor and adjust the commutation angle to an appropriate value.
- The insulation resistance of the intermediate frequency furnace body is low or short-circuited. The resistance of the furnace body is detected by a megohmmeter to eliminate the short-circuit point of the furnace body.
- The resistance of the furnace steel is relatively low, and the resistance of the furnace relative to the induction coil is detected by a megohmmeter; if the resistance is low, the furnace is rebuilt.
