With the increasing prosperity of the general-purpose inverter market, excluding the OEM-imported inverters, the annual usage of general-purpose inverters in China exceeds RMB 2.5 billion, and the installation, commissioning, routine maintenance and repair workload of inverters and their accessory equipment have increased dramatically. Users cause significant direct and indirect losses. This article aims at the causes of the above problems, according to the actual application of a large number of users, from the application environment, electromagnetic interference and anti-jamming, power grid quality, motor insulation and other aspects of the analysis, put forward some suggestions for improvement. 2 work environment issues In actual application of frequency converters, domestic customers install a frequency converter directly at the industrial site to reduce costs, except for a few dedicated customers. The work site is generally full of dust, high temperatures, and high humidity in the south. For the wire and cable industry there are metal dust, corrosive gases and dust in the ceramics, printing and dyeing and other industries. In coal mines and other occasions, there are explosion-proof requirements and so on. Therefore, corresponding countermeasures must be made according to the site conditions. 2.1 Basic Requirements for Installation and Design of Inverter (1) The inverter should be installed inside the control cabinet. (2) The inverter is preferably installed in the middle of the control cabinet; the inverter should be installed vertically, and the large components that may block the exhaust and air intake should be avoided directly above and below. (3) The minimum distance between the upper and lower edges of the inverter and the top, bottom, or partitions of the control cabinet or large components that must be installed should be greater than 300mm. Basic requirements for installing inverters in cabinets (4) If a special user needs to remove the keyboard during use, the keypad hole of the inverter panel must be sealed tightly with tape or replaced with a dummy panel to prevent dust from entering the inverter. (5) Perform regular maintenance on the frequency converter and clean up internal dust in a timely manner. (6) Other basic installation and use requirements must comply with the relevant instructions in the user manual; if in doubt, please contact the corresponding manufacturer's technical support personnel in a timely manner. 2.2 Design Requirements for Dust Control Cabinets It is necessary to use correct and reasonable protective measures when using frequency converters in dusty places, especially in places with multiple metal dusts and flocs, and it is very important to ensure proper operation of the frequency converter. General requirements The control cabinet should be sealed as a whole and should be ventilated through specially designed air intakes and air outlets; the top of the control cabinet should have a protective net and a protective top cover air outlet; the bottom of the control cabinet should have a bottom plate, an air inlet, and a wire inlet, and Install the air filter. (1) The air ducts of the control cabinet should be designed rationally and the air should be discharged smoothly to avoid the formation of eddy currents in the cabinets and dust accumulation in the fixed position. (2) The top cover of the top of the control cabinet shall be equipped with a protective top cover to prevent the sundries from directly falling into it; the height of the protective top cover shall be reasonable and shall not affect the air discharge. The protective air outlet on the side of the protective cover must be equipped with a protective net to prevent floc-like debris from directly falling into the air. (3) If the top side of the control cabinet is used for exhaust, the outlet must be equipped with a protective net. (4) It must be ensured that the axial fan at the top of the control cabinet rotates in the correct direction and the air blows out. If the fan is installed outside the top of the control cabinet, it must be ensured that there is a sufficient height between the protective top cover and the fan; if the fan is installed inside the top of the control cabinet, the screws needed for the installation must use anti-spin springs to prevent the fan from falling off. Damage to internal components and equipment. It is recommended to install plastic or rubber damping washers between the fan and the cabinet, which can greatly reduce the noise caused by fan vibration. (5) Control cabinet front, rear doors and other joints should be sealed with a gasket or sealant to prevent dust from entering. (6) All air inlets and inlet holes in the bottom and side panels of the control cabinet must be fitted with dustproof nets. Block floccular debris entry. Dust nets should be designed to be removable for easy cleaning and maintenance. The dust-proof net has a small mesh, which can effectively block the fine floc (similar to the mesh of a household mosquito screen), or determine the appropriate grid size according to the specific situation. The joints around the dustproof net and the control cabinet must be handled strictly. (7) Regular maintenance of the control cabinet must be carried out to clean up internal and external dust, hair and other debris. The maintenance period can be determined according to the specific circumstances, but it should be less than 2 to 3 months; for dusty places, the maintenance period is recommended to be about 1 month. Dust control cabinet installation requirements 2.3 Design requirements for control cabinets that resist moisture and mildew Most printed circuit board manufacturers, the internal printed circuit board, metal structure parts are not to carry out special treatment against moisture mildew, if the inverter in this state for a long time, the metal structure parts are prone to corrosion, for the conductive copper row in the high temperature operating conditions, Exacerbates the rust process. For the tiny copper conductors on the microcomputer control board and drive power board, due to corrosion will cause damage, so for the application of humid and corrosive gases, there must be basic requirements for the internal design of the inverter, such as printing The circuit board must be coated with three anti-paint sprays. For structural parts, nickel-chromium plating must be used. In addition, other positive, effective, and reasonable measures against moisture and corrosion are also needed. (1) The control cabinet can be installed in a separate, airtight, air-conditioned room. This method is applicable to many control devices. The cost of establishing the equipment room is lower than that of the cabinet body. The control cabinet can be dust-proof as described above. General environment design can be. (2) Adopt independent air inlet. A separate air inlet can be located at the bottom of the control cabinet. It is connected to the external clean environment through an independent closed trench. This method requires installing a dustproof net at the air inlet. If the trench is more than 5m, consider installing a blower. Ferroalloys,
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Frequency converter attention in engineering application