The reason why the induction melting furnace burns the thyristor is mainly caused by the large current and large voltage runaway.
2. The large current is out of control, the back pressure angle of the intermediate frequency voltage is too small, the trigger circuit has poor contact, and the continuity of the off time is also paid attention to.
Now that the quality of the components has passed, the reliability is already very high if the process is good. Inverter thyristors are relatively weak components. If it is damaged frequently, there must be a reason. Should focus on checking:
1) The RC absorption circuit of the inverter tube of the intermediate frequency furnace, focusing on checking whether the absorbing capacitor is open. At this time, a digital multimeter capable of measuring the capacitance should be used to detect the capacitor, and it is not enough to measure only its on and off. If the inverter absorption loop is broken, and the inverter tube is easily damaged;
2) Check whether the electrical parameters of the pipe meet the requirements, and eliminate the use of components flowing into the unqualified manufacturer;
3) Whether the water jacket of the inverter tube and other cooling water channels are blocked, although this situation is rare, it does appear and is easy to ignore.
4) Pay attention to the phenomenon that the load is sparked to the ground. This situation will form a sudden high voltage, causing damage to the inverter tube breakdown.
5) If the running angle is too large or too small, it will cause frequent overcurrent of the inverter tube, which will damage the pipe and cause permanent damage.
6) Without affecting the start-up, properly increase the intermediate frequency loop wiring inductance of the intermediate frequency power supply to the furnace body, which can alleviate the damage caused by the excessive di/dt of the inverter tube.
