How to check the system of medium frequency induction heating equipment
Medium frequency induction heating equipment uses the principle of electromagnetic induction to generate eddy currents in the workpiece placed in the induction coil, so that the workpiece is heated and heated to the desired temperature. The equipment adopts series resonance or parallel resonance, so the power factor is relatively high. Compared with traditional heating methods, it has the advantages of high efficiency and low pollution. This equipment is widely used in forging and metal heat treatment industries. Medium frequency induction heating equipment has a wide range of applications in the fields of diathermy, smelting, quenching, welding, etc. However, due to the large power of the equipment, the electronic components are prone to malfunction due to overheating. How can people perform system inspections on the heating equipment.
Power supply: Use a multimeter to check whether there is electricity behind the main circuit switch (contactor) and control fuse, which will rule out the possibility of disconnection of these components.
Rectifier: The rectifier uses a three-phase fully controlled bridge rectifier circuit, which includes six fast fuses, six thyristors, six pulse transformers and a freewheeling diode. There is a red indicator on the quick-acting fuse. Normally, the indicator is retracted inside the shell. When the quick-acting blows, it will pop up. Some quick-acting indicators are tight. When the quick-acting blows, it will get stuck inside. , So for the sake of reliability, you can use a multimeter to test the fast-blow on/off gear to determine whether it is blown.
Inverter: The inverter includes four fast thyristors and four pulse transformers, which can be inspected as described above.
Transformer: Each winding of each transformer should be connected. Generally, the resistance of the primary side is about tens of ohms, and the secondary resistance is a few ohms. It should be noted that the primary side of the medium frequency voltage transformer is connected in parallel with the load, so its resistance value is zero.
Capacitors: The electric heating capacitors connected in parallel with the load may be broken down. The capacitors are generally installed in groups on the capacitor rack. The group of the broken capacitors should be determined first when checking. Disconnect the connection point between the bus bar of each group of capacitors and the main bus bar, and measure the resistance between the two bus bars of each group of capacitors. Normally, it should be infinite. After confirming the bad group, disconnect the soft copper skin of each electric heating capacitor leading to the bus bar, and check one by one to find the broken capacitor. Each electric heating capacitor is composed of four cores. The shell is one pole, and the other pole is led to the end cover through four insulators. Generally, only one core will be broken down, and the lead on this insulator will be jumped off. The capacitor can continue to be used, and its capacity is 3/4 of the original. Another fault of the capacitor is oil leakage, which generally does not affect the use, but pay attention to fire prevention. The angle steel where the capacitor is installed is insulated from the capacitor frame. If the insulation breakdown will ground the main circuit, measure the resistance between the capacitor shell lead and the capacitor frame to determine the insulation status of this part.