With the development and promotion of medium frequency induction furnace technology, the demand in the field of metal hot processing is increasing; the medium frequency furnace uses the principle of electromagnetic induction during operation, which is more energy-saving and environmentally friendly than traditional coal-fired furnaces. In the later use of the medium frequency furnace, basic maintenance and management are required to avoid the equipment failing to start normally, abnormal sounds, thyristor burnout, etc.
(1) Check and clean the radiator to maintain efficient cooling effect, and perform pickling if necessary
(2) Check whether the water cooling system is blocked and leaking, whether the water pressure relay is sensitive, and the inlet water temperature difference should generally not be greater than 35℃. The medium frequency power supply, induction coil, water cable, etc. all need to be cooled with water, so water is essential for furnace equipment. The probability of furnace equipment damage caused by cooling water failure is relatively high. Because most of the cooled devices are charged bodies, such as thyristors, induction coils, water cables, etc., the conductivity of the cooling water directly cooling these devices must be lower than the specified value, and the connecting hose must be a carbon-free hose. In addition, the inlet temperature, outlet temperature, water pressure and flow rate of the cooling water must comply with the design requirements. The cooling water system of the electric furnace is equipped with various sensors to monitor the relevant parameters of the cooling water. When the cooling water parameters are abnormal or exceed the set value, an alarm will be sounded or the equipment will be stopped.

The cooling water pump station of the medium frequency electric furnace must be equipped with two main water pumps of the same specifications (one for use and one for backup), and must be equipped with an emergency cooling water system. When the main water pump cannot work due to a power outage in the power grid, the emergency cooling water system can provide cooling for the furnace body to avoid damage to the furnace body.
(3) Check the insulation of the induction coil and whether there is any water leakage
(4) Check whether the wires and switches are damaged
(5) Check and clean the sink, check the drain valve, and remove some sewage to prevent scaling
(6) Clean the oil and dust of various electrical components and other equipment, and use a fan or air pump to remove dust
(7) Check whether the wiring screws are tightened to ensure good contact
(8) Check whether the thyristor, electrical circuit bus, transformer and each line segment are overheated
(9) Hydraulic system
The hydraulic system of the medium frequency coreless induction furnace is used to tilt the furnace to pour out the molten metal liquid, as well as to open and close the furnace cover. To ensure reliable operation, the hydraulic station of the furnace should be equipped with two main pumps of the same specifications (one for use and one for backup). A throttle valve should be installed at the inlet end of the tilting hydraulic cylinder to prevent the furnace body from falling suddenly due to loss of pressure in the hydraulic system. In the case of a long power outage, the molten metal in the furnace may cool and solidify, which may damage the furnace lining. It is very dangerous to melt the solidified metal in the furnace by running the furnace. Therefore, the hydraulic system of the furnace should be equipped with an emergency system. When the power supply of the power grid is interrupted, if necessary, the emergency system can be used to pour out the molten metal in the furnace to prevent it from solidifying in the furnace.
(10) Grounding leakage furnace monitoring alarm
During the operation of the coreless medium frequency induction furnace, if the furnace lining is damaged, it will cause a leakage accident. If the molten metal leaks from the furnace lining, it will damage the insulation, coil support and yoke of the induction coil. If it is not discovered in time, it will cause serious leakage. If the molten metal burns the copper tube of the coil, the water in the tube will contact the molten metal and cause an explosion, resulting in a serious accident. It can be seen that it is absolutely necessary to set up a furnace lining leakage alarm system. At present, the better one is the DC injection leakage alarm system. The center point of the secondary side of the transformer is not grounded, so a DC circuit can be connected in parallel to the AC power supply circuit of the induction coil. The molten metal in the furnace is grounded through the furnace bottom electrode, and the induction coil is connected in series with the DC power supply and milliammeter and grounded, so the molten metal, furnace lining, coil and milliammeter are connected to form a DC circuit. When the furnace lining is in good condition, the milliammeter display value is very small due to the large resistance of the furnace lining; if the furnace lining is in poor condition and molten metal penetrates into the furnace lining and approaches the induction coil, the resistance of the furnace lining will decrease and the indication value of the milliammeter will increase. When the current value exceeds the set value, an alarm will be issued and the main power supply will be cut off, thus preventing the occurrence of furnace leakage accidents.
(11) Automatic fault diagnosis
Modern induction furnaces are equipped with a computer management system. This system has an automatic fault diagnosis function. The system scans each setting point of the equipment. When the parameters of the setting point are found to be abnormal, an alarm will be issued and the fault information can be displayed and recorded. Since the scanning speed is very fast, reaching hundreds of times per minute, the fault will be discovered in its initial state, so that the fault will not cause serious equipment damage. Relevant information about the fault will be stored in the computer for future reference.

Medium frequency induction furnaces are widely used in real life, which is inseparable from their good maintenance methods.
First, do a good job of inspection before starting, especially for the furnace lining, check whether it is intact, and inspect cracks, furnace mouth, erosion, furnace nozzle, etc. to ensure normal startup.
Secondly, before putting in pig iron, the amount of scrap steel to be put in should be determined according to the impact degree of pig iron on the furnace bottom. After the iron is melted, recarburizer, scrap steel and return to the furnace can be added.