( 1 ) Observe the cooling water (temperature, water pressure, flow) on the internal and external circulating water systems at any time. 

If it is found that a branch has small water flow, leakage, blockage, or too high temperature, it should reduce power operation or stop processing; if it is found that the furnace cooling system is out of power or the pump is stopped, the cooling water of the furnace body should be stopped. Immediately stop melting and; 

a , start the pump with the backup power; 

b , or start the emergency diesel generator power supply to start the emergency circulation cooling system; 

c , or open the tap water (or emergency water tank) directly into the cooling (while opening the drain), directly discharge the water after cooling through the furnace; 

d , can not be processed in a short time, the water cycle is difficult to recover, then the molten iron in the furnace should be emptied to avoid the iron block becoming iron block due to the long-term cooling of the molten iron, which is difficult to remove from the furnace; 

( 2 ) Observe the various indicator instruments on the power cabinet door of the intermediate frequency furnace at any time, and adjust the input of the intermediate frequency power in time to obtain the best melting effect and avoid long-term low-power operation.

( 3 ) Pay close attention to the current indication value of the leakage current indicator to grasp the change of the thickness of the lining. When the indicator needle reaches the police value, it should be rebuilt. 

( 4 ) If the protection indication suddenly appears during normal operation, first turn the power knob to the minimum position, and immediately press “ inverter stop ” to find out the cause and then start it after elimination. 

( 5 ) If there is an emergency or abnormal situation, such as abnormal sound, smell, smoke, fire or a sharp drop in output voltage, the output current rises sharply, and the intermediate frequency is higher than normal operation, leakage current (hearth alarm) The value fluctuates greatly. It may be that the furnace lining is thin, leakage of molten iron, and the induction ring gate is short-circuited by arc. It should immediately stop by the “ inverter stop ”button and deal with it in time to prevent the accident from expanding. 

( 6 ) When adding and slag, the power should be adjusted first. When the iron is discharged from the furnace, the variable frequency power supply must be placed in the “ inverter stop ” position. 

( 7 ) When the cold lining of the hot lining is melted, the charging can only be installed to 50 % of the height of the crucible . When the current is reduced until the voltage can be raised to the rated value, the feeding is continued.(This is because the cold resistance of the cold charge is small, the current is large, and the regulated voltage is limited by the current to affect the power input). 

( 8 ) During the production process, it is not allowed to overfill or even exceed the furnace mouth. Because the magnetic field of the furnace above the upper end of the induction coil is weak, it is mainly heated by the heat transfer from the lower iron, so the melting speed is slow. At the same time, because the furnace cannot be covered, a large amount of heat is dissipated through the furnace mouth, reducing productivity. 

In addition, the upper end of the induction coil and the lining of the joint with the nozzle are not easy to be compacted, the oven is not perfect, and the sintering is not good, but the mechanical vibration stress is the largest, so the furnace is likely to leak. Therefore, the surface of the solution in the crucible should be controlled to be flush with the upper end surface of the induction coil. 

( 9 ) Although the medium frequency furnace can be emptied, it is good for melting different materials. However, if the material is not replaced, it is better to leave a residual liquid in the furnace. This is because, due to the presence of molten iron in the furnace, the added charge is easily connected into a large number of pieces, and the single charge is welded together by arc bridge to form a large piece, thereby increasing the melting rate. The speed of the arc bridge between a single small charge depends on the frequency. The frequency is low and the lap welding speed is low (the power frequency furnace must leave the residual liquid melting). If it is not emptied, a small portion of the molten iron is left at the bottom of the furnace, which can be easily overcome by using the disadvantages of lower frequencies (the intermediate frequency furnace frequency is relatively low). In addition, since the residual liquid is small in the initial stage of energization, high power can be input from the beginning, and at least the melting time of the metal charge can be shortened.    

( 10 ) When feeding, the maximum surface of the molten iron should be avoided beyond the limit of 80 % capacity, and the accident will not occur when the molten iron overflows the furnace mouth during feeding. 

( 11 ) Adding materials should first add small pieces of furnace charge and then increase the amount of charge. 

( 12 ) Frequently observe the melting condition in the furnace. The material should be replenished in time before the furnace material is completely melted. It is found that the scaffold should be treated in time to avoid the furnace under the roof due to the sharp rise of the temperature of the molten iron and exceeding the melting point of the furnace material (silica sand 1704 °C ). 

( 13 ) After the molten iron is melted, it should be slag and temperature measured in time, and the temperature at which the furnace is discharged should be released in time. 

( 14 ) Under normal circumstances, when the wall of the original lining is 1/3 of the original lining, the furnace should be rebuilt. 

( 15 ) The molten iron should be emptied every week to measure the size of the lining and observe the surface condition. The actual situation of the lining should be grasped in time, and the problems should be dealt with in time. 

( 16 ) by a carbon agent is preferably added little by little during the addition of the metal charge. If it is added too early, it will adhere to the bottom of the furnace and will not dissolve easily into the molten iron. If it is added too late, it will prolong the melting and heating time, which will not only cause delay in composition adjustment, but also may cause excessive high temperature. Ferrosilicon is added (by Si ), the stirring force is weak frequency furnace, because molten iron containing Si amount of the high gain causes C is not good, and therefore Si iron added later this as well, but will cause the liquid iron in the furnace Delay in composition analysis and adjustment. 

( 17 ) Retaining liquid metal in the furnace during melting helps to improve the electrical efficiency of some electric furnaces and improve the power factor of the melting stage. However, these molten iron may endanger the metal quality due to overheating in the furnace for a long time, so the residual metal liquid is preferably 15 % of the furnace capacity . Too little molten iron is overheated, and too much reduces the effective use of molten iron and increases unit energy consumption. 

( 18 ) The thickness of the charge is preferably 200 to 300 mm . The greater the thickness, the slower the melting.