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How to deal with the fault of thyristor in intermediate frequency induction furnace?

Author:admin      Time:2018-11-03 08:54
1. fault 1
 
Failure: after switching thyristor, the thyristor can be destroyed when the switch is switched on. Analysis and disposal: The device burns thyristor when it breaks down. Don't start it immediately after replacing the new thyristor. First, the equipment should be checked systematically to remove the fault. After the device is confirmed to be open, it will avoid burning the thyristor again. When pressing a new thyristor, we must pay attention to pressure balance, otherwise it will cause mechanical damage to the inner chip of the thyristor, which will lead to a sharp decline in the voltage withstand value of the thyristor, and the phenomenon of burning the thyristor as soon as it starts.
 
2. fault 2
 
Fault: after the replacement of the new thyristor, the boot is normal, but the thyristor is burned again for a period of time. Analysis and treatment: the reasons for this failure are as follows. (1) the thermal characteristics of the electrical components of the control part are not good. (2) dislocation of SCR and radiator installation. (3) the radiator has been repeatedly pressed or installed on the small mesa thyristor, resulting in the concave center of the radiator. The contact between the radiator and the thyristor is poor and the thyristor is destroyed. (4) the scale of radiator water is too thick and the heat conduction is poor, resulting in overheating of components. (5) The temperature of fast thyristor rises because of bad heat dissipation, and the turn-off time of thyristor increases with the increase of temperature, which eventually leads to the inversion and burning of thyristor. (6) Thyristor operating temperature is too high, gate parameters are reduced, anti-interference ability is reduced, easy to produce false trigger, damage thyristor and equipment. (7) To check whether the resistance-capacitance absorption circuit is in good condition, special attention should be paid to: the inverted absorption capacitor is charged by a 2500V insulated rocker, and then the discharge status can be compared with the conductor, the capacity failure can be found out and replaced, and the failure may not be detected by the multimeter.