Overhaul of IF induction heating equipment that does not work properly after startup

The IF induction heating equipment does not work properly after startup, and generally manifests itself in the following two aspects: phase loss of the rectifier and failure of the induction coil.

(1) Phase loss of the rectifier: The fault is manifested as abnormal sound during operation, the maximum output voltage does not rise to the rated value, and the strange noise of the power cabinet becomes louder. At this time, the output voltage can be lowered to about 200V. The output voltage waveform (the oscilloscope should be placed on the power supply synchronization), the input voltage waveform has six waveforms per cycle under normal conditions, and two in the absence of phase. This fault is usually caused by a thyristor of the rectifier that has no trigger pulse or trigger non-conduction. At this time, you should first look at the gate pulses of the six rectifier thyristors using an oscilloscope. Take a look at each gate resistor and replace the thyristor that is not open or has a particularly large gate resistance.

(2) Induction coil failure: The induction coil is a load of an intermediate frequency power supply. It is made of a square copper tube with a wall thickness of 3 to 5 mm. Its common failures are as follows:

a. The induction coil leaks water, which may cause ignition between the turns of the coil, and it must be repaired in time to run.

b. The molten steel sticks to the induction coil. The steel slag is hot and red, which will cause the copper tube to burn through. It must be removed in time.

c. Inter-turn short circuit of induction coil, this kind of fault is especially easy to happen on small intermediate frequency induction furnace, because the furnace is small, it will be deformed by the thermal stress during work, resulting in short-circuit between turns. When high.