中频电炉具有感应加热装置的浇往的铸造生产线的出现，浇注工序机械化和自动化的要求更为迫切.准确的浇注温度是保证获得高质量铸件的重要条件，能贮存一定量金属液的浇注护有利于组织生产。因此，各国近20年来相继开发出来的气压式、塞杆式、气压一塞杆式以及电磁泵式保温浇注护，迅速改变了铸造浇注工序的落后面貌，提高了铸件质量，减少了废品，取得了良好的经济效果.
The
application of intermediate frequency electric furnaces with induction
heating devices for pouring protection is rapidly expanding. With the
emergence of various high-efficiency casting production lines, the
requirements for mechanization and automation of the pouring process are
becoming more urgent. Accurate pouring temperature is an important
condition to ensure the acquisition of high-quality castings, and
pouring protection that can store a certain amount of molten metal is
beneficial for organizing production. Therefore, in the past 20 years,
various countries have successively developed air pressure, plug rod,
air pressure one plug rod, and electromagnetic pump insulation casting
protectors, which have quickly changed the outdated appearance of the
casting and pouring process, improved the quality of castings, reduced
waste, and achieved good economic results
由于中频电炉功率密度高，无相平衡装置，土建费用小。因此，在国外相同生产率的中频感应电护的初次投资费用较工频感应电炉低10%一15%。从冶金学角度看，在中a感应电护内熔化的金属只存在“一次过热”现象
Due
to the high power density of the intermediate frequency electric
furnace and the lack of phase balance devices, the civil engineering
cost is low. Therefore, the initial investment cost of intermediate
frequency induction furnaces with the same productivity abroad is 10% to
15% lower than that of industrial frequency induction furnaces. From
the perspective of Metallurgy, the molten metal in the induction
protection of medium a only has the phenomenon of "once overheating