The induction melting furnace cannot work normally after starting, usually manifested in the following aspects:
1. Phase loss of the rectifier: The fault is manifested as an abnormal sound during operation. The larger output voltage rises below the rated value. When the power cabinet emits abnormal noise, the output voltage can be reduced to about 200V, and the output of the rectifier can be observed with an oscilloscope Voltage waveform (the oscilloscope should be placed in the power supply). When the input voltage waveform is normal, there are six waveforms per cycle, and two will be lost when the phase is missing. This kind of fault is usually caused by some rectifiers. Only the thyristor has no trigger pulse or the trigger is not turned on. At this time, you should use an oscilloscope to view the gate pulses of the six rectified thyristors. If so, please use a multimeter to measure the resistance of each grid below 200Ω after it is turned off, it will be blocked, or the crystal with extremely high grid resistance only needs to replace the brake tube.
2. Inverter three bridge arms work: the output current is very large, the furnace is the same when the furnace is empty, the power cabinet is very loud during operation, and it appears as a fault. After starting, turn the power knob to a smaller position, and you will find the induction melting furnace The output voltage is higher than the normal level. Use an oscilloscope to observe the voltage waveform between the anode and cathode of the four inverter thyristors. If the three bridge arms are working, you can see that the two adjacent thyristors in the inverter will produce waves. .
3. Induction coil failure: The induction coil is the load of the induction melting furnace. It is made of a square copper tube with a wall thickness of 3 to 5 mm. The common failures are as follows:
The induction coil leaks water, which may cause a fire between the coil turns, so it must be repaired in time. The molten steel sticks to the induction coil and the steel slag becomes hot and red, which will cause the copper tube to burn. It must be cleaned in time, and the induction coil is short-circuited. This kind of failure is particularly easy to occur in small induction melting furnaces, because the furnace is small and will be heated during operation.
Due to the deformation caused by the force, the short circuit between the turns is caused. The fault is manifested as a higher current and higher operating frequency than usual. In summary, in order to be able to use the correct method to repair the fault of the induction melting furnace, you must be familiar with induction The characteristics and causes of the common failures of the melting furnace, so as to avoid detours, save time, troubleshoot as soon as possible, and restore the normal operation of the induction melting furnace, so as to ensure the smooth progress of production.