What is the cause of abnormal start of medium frequency electric furnace?

　　Lack of phase of rectifier: the fault is that the sound is abnormal during operation, the larger output voltage rises below the rated value, and the abnormal noise announced by the power cabinet is becoming larger and larger. At this time, the output voltage can be reduced to about 200V, and the output of the rectifier can be investigated through the voltage waveform of the oscilloscope. Generally, the input voltage waveform of medium frequency electric furnace has six waveforms in each cycle, while two waveforms disappear in case of phase loss. You should use an oscilloscope to check the grid pulse of six rectifier thyristors. If yes, please use a multimeter to measure 200 Ω after sealing. Click on each grid resistance and replace the blocked thyristor or thyristor with a particularly high grid resistance.

　　Three arm operation of frequency converter: after the medium frequency electric furnace is started, the problem is that the output current is too large, the furnace is the same when empty, and the power cabinet makes a loud noise when the power cabinet works. Adjust the furnace power knob to a smaller position, and you will find that the intermediate frequency output voltage ratio is generally very high. The voltage waveform between anode and cathode of four inverter thyristors is investigated by oscilloscope. If the three bridge arms work, you will find that two adjacent thyristors in the inverter have normal waveform, as long as the two adjacent thyristors have no waveform and the other is sine wave.

　　Induction coil fault: the induction coil of medium frequency furnace is the load of medium frequency power supply. It is made of square copper tubes with a wall thickness of 3 to 5 mm. The common faults are as follows: the induction coil of medium frequency furnace leaks water, which may lead to ignition between coil turns, which needs to be repaired and welded in time. If the molten steel of the medium frequency furnace sticks to the induction coil, the steel slag becomes hot and red, resulting in the burning of the copper pipe, which needs to be sorted out in time.

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