Eight precautions for using high-voltage control cabinets
2025-10-21
1. Proper grounding of the high-voltage control cabinet is an important means to improve the sensitivity of the control system and suppress noise. The smaller the grounding resistance of the grounding terminal E (G) of the high-voltage frequency conversion cabinet, the better. The cross-sectional area of the grounding wire should not be less than 2mm2, and the length should be controlled within 20m. The grounding of the frequency converter must be separated from the grounding point of the power equipment and cannot be grounded together. The shielding layer of the signal input line should be connected to E (G), and its other end must not be connected to the ground terminal, otherwise it will cause signal fluctuations and cause the system to oscillate continuously. The high-voltage frequency conversion cabinet and the control cabinet should be electrically connected. If there are difficulties in actual installation, copper core wires can be used for bridging.
2. Vibration and impact. When the control cabinet equipped with a variable frequency cabinet is subjected to mechanical vibration and impact, it can cause poor electrical contact. At this point, in addition to improving the mechanical strength of the control cabinet and keeping it away from vibration and impact sources, anti-seismic rubber pads should also be used to fix components such as electromagnetic switches that generate vibration outside and inside the control cabinet. After the equipment has been running for a period of time, it should be inspected and maintained.
3. Prevent overvoltage at the input terminal. The power input terminal of high-voltage frequency conversion cabinets often has overvoltage protection. However, if the high voltage is applied to the input terminal for a long time, it will cause damage to the input terminal of the high-voltage frequency conversion cabinet. Therefore, in practical applications, it is necessary to verify the input voltage, single-phase or three-phase, and the rated voltage used by the high-voltage frequency converter cabinet. Especially when the power supply voltage is very unstable, there should be a voltage regulator device, otherwise it will cause serious consequences.
4. Electrical environment, physical environment, and ambient temperature. When the temperature is too high and the temperature changes greatly, condensation is prone to occur inside the high-voltage variable frequency cabinet, which greatly reduces its insulation performance and may even cause short circuit accidents. If necessary, desiccants and heaters must be added to the box.
5. Corrosive gases. If the concentration of corrosive gases is high in the usage environment, it will not only corrode the leads of electronic components, printed circuit boards, etc., but also accelerate the aging of plastic components and reduce insulation performance. In this case, the control box should be made into a closed structure and ventilated
6. Working temperature. The interior of the high-voltage frequency converter cabinet contains high-power electronic components that are easily affected by operating temperature. The product generally requires a temperature range of 0-55 ℃, but in order to ensure safe and reliable operation, it should be considered to leave room for use and controlled below 40 ℃. In the control box, the installation of the high-voltage frequency converter cabinet should strictly follow the installation requirements in the product manual, and it is absolutely not allowed to install heating elements or components that are prone to heating against the bottom of the frequency converter.
7. Prevent electromagnetic wave interference. During operation, the frequency converter generates a lot of interference electromagnetic waves due to rectification and inversion, which can cause certain interference to nearby instruments and meters. Therefore, the instruments and electronic systems inside the cabinet should be equipped with metal casings to shield the interference of high-voltage frequency conversion cabinets on the instruments. All components should be reliably grounded. In addition, shielded control cables should be used for the connections between electrical components, instruments, and meters, and the shielding layer should be grounded. If electromagnetic interference is not handled properly, it often renders the entire system inoperable, resulting in control unit failure or damage.
8. In high-voltage frequency conversion cabinets, lightning absorption networks are generally installed to prevent instantaneous lightning intrusion and damage to the frequency converter. However, in practical work, especially when power lines are overhead, relying solely on the absorption network of the frequency converter cannot meet the requirements. In areas with active lightning, this issue is particularly important. If the power supply is an overhead incoming line, a frequency conversion dedicated lightning arrester (optional) should be installed at the incoming line, or a steel pipe should be pre embedded 20 meters away from the frequency converter for dedicated grounding protection according to specifications. If the power supply is introduced through cables, a lightning protection system should be installed in the control room to prevent lightning from entering and damaging the equipment. Practice has shown that it can effectively solve the problem of lightning strikes.
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