1 ton medium frequency electric furnace electrical safety protection measures
1.1 ton medium frequency electric furnace cooling water system
SCR intermediate frequency power supplies, induction coils, water cables, etc. all require water for cooling, so water is critical for medium frequency electric furnace equipment. The probability of damage to the furnace equipment due to a malfunction of the cooling water is high. Since the cooled devices are mostly charged bodies, such as thyristors, induction coils, water cables, etc., the conductivity of the cooling water that directly cools these devices must be lower than the specified value, and the connecting hose must be a carbon-free hose. In addition, the inlet water temperature, outlet water temperature, water pressure and flow rate of the cooling water must comply with the design regulations. The electric water cooling system of the electric furnace is provided with various sensors to monitor the relevant parameters of the cooling water. When the cooling water parameter is abnormal and exceeds the set value, it will alarm or stop the equipment.
The cooling water pumping station of the intermediate frequency electric furnace shall be equipped with two main water pumps of the same specification (one for one), and must be equipped with an emergency cooling water system. When the main power pump fails to work due to power grid interruption, the emergency cooling water system can provide cooling for the furnace body to avoid damage to the furnace body.
2.1 ton medium frequency electric furnace hydraulic system
The hydraulic system of the 1 ton medium frequency electric furnace is used to pour out the molten metal and to open and close the lid. In order to ensure reliable operation, the hydraulic station of the electric furnace should be equipped with two main pumps of the same specification (one for one). A throttle valve is required at the inlet end of the tilting cylinder to prevent the furnace body from suddenly falling due to the pressure loss of the hydraulic system. In the case of long power supply interruption time, the molten metal in the electric furnace may be cooled and solidified. This may damage the lining. If the electric furnace is used to melt the metal solidified in the furnace, it is very dangerous. The hydraulic system should be equipped with an emergency system. When the power supply to the grid is interrupted, if necessary, the emergency system can be used to pour the molten metal in the furnace to avoid solidification in the furnace.
3.1 ton medium frequency electric furnace ground leakage furnace monitoring alarm
In the operation of the coreless medium frequency electric furnace , if the lining is damaged, it will cause a furnace accident. If the molten metal leaks out of the furnace lining, it will damage the insulation of the induction coil, the coil strut and the yoke. If it is not found in time, it will cause serious leakage. If the molten metal burns the coil copper tube, the contact of the water in the tube with the molten metal may cause an explosion, causing a serious accident. It can be seen that it is absolutely necessary to set up the furnace lining furnace alarm system. At present, the DC injection type leakage alarm system is better. 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 loop of the induction coil. The molten metal in the furnace is grounded through the bottom electrode of the furnace, and the induction coil is connected in series with the DC power source and the milliampere meter, so that the molten metal, the lining, the coil and the milliampere meter are connected into a DC loop. When the lining is in good condition, the mA meter shows a small value due to the large resistance of the lining; if the lining condition is poor, if the molten metal penetrates into the lining and approaches the induction coil, the resistance of the lining will decrease, mA The indication value of the table becomes larger. 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 a leak accident.
4.1 ton medium frequency electric furnace automatic fault diagnosis
The modern medium frequency electric furnace is equipped with a computer management system. This system has automatic fault diagnosis. The system scans each set point of the device. When the parameter of the set point is 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, hundreds of times per minute, the fault is discovered in its initial state, so that the malfunction does not cause serious equipment damage. Information about the failure has been stored on the computer for future reference.
In addition to the above listed, there are other safety measures, such as when the door of the thyristor IF power supply is opened, the incoming line power is automatically cut off by the mechanical interlock; and if each capacitor is equipped with a pressure switch, When the internal pressure of the capacitor exceeds the set value, it will alarm and cut off the power supply to prevent the capacitor from exploding due to excessive internal pressure.
Although various safety measures have been taken on the medium frequency electric furnace equipment, in order to ensure safety, it is necessary to have a management system to improve the safety awareness of personnel.
