Abstract : Based on the actual situation of frequency converters used in aluminum smelting enterprises, this paper proposes suggestions on the use of frequency converters from the aspects of application environment, electromagnetic compatibility, power grid quality and motor insulation, and points out the issues that should be paid attention to.
Keywords : frequency converter; operating environment; interference
0 Introduction
In recent years, with the rapid development of domestic aluminum smelting enterprises, the use of frequency converters has become increasingly widespread. This has led to a surge in the workload of installing, commissioning, maintaining, and repairing frequency converters and their auxiliary equipment. While bringing benefits and convenience to users, this has also created some problems and misconceptions about their use. In practical applications of frequency converters in industrial enterprises, except for a few with dedicated frequency converter rooms, most applications, in order to reduce costs or due to limitations in installation conditions and processes, directly install frequency converters on the industrial site. For example, the frequency converters for the multi-functional overhead cranes in our electrolysis and roasting workshops are installed on the crane beams, next to the fans for flue gas purification in the electrolysis and roasting workshops, and next to various water pumps and air compressors. The working environment of frequency converters generally presents problems such as high dust levels, high temperatures, high humidity, strong magnetic fields, and occasional corrosive gases. The working environment of frequency converters has a significant impact on their proper operation; therefore, when using frequency converters, appropriate measures must be taken based on the actual site conditions.
1. Installation and design of frequency converters
1.1 Basic Requirements for Inverter Installation Design
① The frequency converter should be installed inside the control cabinet, and the sealing and heat dissipation of the electrical cabinet should be properly addressed.
② The frequency converter is best installed in the middle of the control cabinet and vertically. Large components that may block the exhaust and intake air should be avoided directly above and below it.
③ The minimum distance between the inverter housing and the inner wall of the control cabinet should be greater than 300mm. If other electrical components are installed in the same cabinet, the distance between them should also be greater than 300mm.
④ If the keyboard needs to be removed during use, the keyboard hole on the inverter panel must be sealed tightly with tape or replaced with a dummy panel to prevent a large amount of dust from entering the inverter.
⑤ The frequency converter should be maintained regularly, and internal dust should be cleaned in a timely manner.
⑥ You must comply with the instructions on basic installation and use in the user manual. If you have any questions, you should contact the relevant manufacturer in a timely manner.
1.2 Design requirements for dust control cabinet
When using frequency converters in dusty environments, proper and reasonable protective measures should be taken to ensure their normal operation. The control cabinet should be completely sealed and ventilated through specially designed air inlets and outlets. The top of the control cabinet should have a protective net and a protective top cover with an air outlet, while the bottom of the control cabinet should have a base plate, an air inlet, and a cable entry hole, and be equipped with a dustproof net.
① The air duct of the control cabinet should be reasonably designed to ensure smooth ventilation and avoid the formation of eddies inside the cabinet, which would cause dust to accumulate in fixed locations.
② A protective cover should be installed above the air outlet on the top of the control cabinet to prevent debris from falling directly in; the height of the protective cover should be reasonable and should not affect ventilation. Protective nets should be installed on the side air outlets of the protective cover to prevent fibrous debris from falling directly in.
③ If the top side exhaust method of the control cabinet is adopted, a protective net must be installed at the air outlet.
④ Ensure the axial fan on top of the control cabinet rotates in the correct direction, drawing air outwards. If the fan is installed on the outside of the control cabinet top, ensure sufficient space between the protective cover and the fan. If the fan is installed inside the control cabinet top, use anti-reverse springs for the screws to prevent the fan from falling off and damaging components and equipment inside the cabinet. It is recommended to install plastic or rubber vibration damping washers between the fan and the cabinet to minimize noise caused by fan vibration.
For details, please click: Issues to be aware of when selecting frequency converters for aluminum smelting enterprises.
