Shennai medium frequency furnace maintenance knowledge

Jun 29, 2022


The most common problems when the medium frequency furnace often breaks down are the virtual connection of the wiring

The most common problems when the medium frequency furnace often breaks down are the virtual connection of the wiring, the failure to tighten the screws, the water cut-off, the burnout of a device, etc. In order to shorten the maintenance time, shennai medium frequency furnace constantly summarizes the experience during maintenance, is diligent in observation, and also needs to master some maintenance skills.

1. observe the instrument parameters of the equipment during operation, and whether there is any appearance phenomenon such as heating, redness and loose screws in the equipment. Here, the relationship between instrument parameters and equipment operation status is mainly introduced. During the operation of the intermediate frequency power supply, there is a close relationship between the intermediate frequency voltage, DC voltage and DC current. Whether the intermediate frequency power supply operates normally can be determined by observing the parameters of the three instruments. We know that the product of DC voltage and DC current is the intermediate frequency power, and the ratio of DC voltage and DC current can reflect the impedance matching state of the load. For example, for 250KW medium frequency equipment, the highest average value of DC voltage is 513v and the highest average value of DC current is 500A. If the DC voltage reaches 500V and the DC current is 500A when the equipment is running, its impedance reaches the best matching value. If the DC current is less than 500A, the impedance value is high; if the DC current is greater than 500A, the impedance value is low. That is to say, the matching condition of load impedance can be seen by observing the value of DC current and DC voltage. The ratio of DC voltage to intermediate frequency voltage can reflect the working state of the inverter. For example, if the DC voltage is 510v and the intermediate frequency voltage is 700V, the leading angle of the inverter is 36 °. We use 700V / 510v=1.37. Generally, the ratio of intermediate frequency voltage to DC voltage is between 1.2 ~ 1.5. We all think that the inverter works normally. If the ratio is less than 1.2, the leading front angle is too small and the inverter is difficult to commutation; If it is greater than 1.5 times, the leading angle is too large, and the equipment may fail.

2. listen to whether there is noise, whether the sound is continuous and whether there is dull reactor vibration in the medium frequency furnace whistle; The second is to listen to whether there is a fire sound, which is different from the usual sound.

3. understand the condition of the equipment in case of failure, and try to be as detailed as possible. At the same time, understand the operation condition of the equipment before failure.

4. it refers to measuring the waveform, voltage, time, angle, resistance and other parameters of each point with oscilloscope, multimeter and other test instruments to determine the cause of the fault. It is forbidden to directly run the equipment without any inspection after finding the fault point, because there are often other deeper reasons behind the fault point.