Thyristor is an important component in IF electric furnace. It can also be said that the heart of IF electric furnace is thyristor. Its correct use is very important to the operation of the equipment. We must be familiar with the common sense of the use of SCRs in intermediate frequency electric furnaces, so as to avoid frequent burning of silicon and shutdown of electric furnaces, which will affect production. The working current of the SCR of the intermediate frequency furnace ranges from several hundred amperes to several thousand amperes, and the voltage is usually between one and two thousand volts. Good main control board protection of the intermediate frequency power supply and good circulating water cooling conditions are necessary.
The table of the SCR radiator of the intermediate frequency furnace must match the size of the SCR table to prevent the contact surface from being biased or crooked, which will damage the thyristor contact surface. The SCR radiator table of the intermediate frequency furnace must have high flatness and smoothness. During the installation, the thyristor table and the radiator table should be kept clean, clean and free of dirt and other dirt.
During the installation of the SCR of the intermediate frequency electric furnace, the surface of the silicon component and the surface of the radiator must be kept completely parallel and concentric. During the installation, it is required to apply pressure through the center line of the component so that the pressure is evenly distributed throughout the entire contact area. Use a torque wrench to alternately and uniformly apply force to all fastening nuts, and the pressure must meet the specified requirements.
The SCR radiator structure of the IF furnace is a water-cooled cavity + multiple copper pillars. If the circulating water is too hard, it will scale in the water cavity of the SCR radiator of the IF furnace, resulting in poor heat dissipation. The entry of leaves and other debris can also cause poor water flow.
The correct installation pressure of the SCR of the intermediate frequency electric furnace is 150-200KG / cm2. When the SCR is assembled with the radiator at the factory, it is usually press-fitted with an oil hydraulic machine. When the tool is pressed, there is no need to worry that the silicon will be crushed, but the silicon will be burned due to poor heat dissipation.
The factory test temperature of the SCR of the intermediate frequency furnace is 100 ° C (junction temperature). Generally, the circulating water temperature of the electrical cabinet of the intermediate frequency furnace is maintained below 40 ° C to ensure its normal operation. A handheld infrared thermometer is very useful, 350 ℃ thermometer is only a few hundred yuan, not too expensive. Use it to measure the temperature of the thyristor and the radiator of the working power supply, you can find the abnormal points in time, and handle the fault.
的 Overload characteristics of SCR in IF electric furnace: The damage of SCR is called breakdown. Under normal water-cooling conditions, the current overload capacity can reach more than 110%; no voltage overload capacity, that is, silicon is definitely damaged under the condition of overvoltage, and then considering the surge voltage, when manufacturers manufacture equipment, Often, silicon components are selected according to the value of 3-4 times the operating voltage. For example, when the rated operating voltage of the intermediate frequency furnace cabinet is 750V, two silicon components with a withstand voltage of 1400V are selected to work in series, which is equivalent to a withstand voltage of 2800V.