With the growing prosperity of the general frequency converter market, excluding the OEM imported frequency converter, the annual consumption of general frequency converter in China has exceeded 5 billion yuan, and the installation, commissioning, daily maintenance and repair work of frequency converter and its auxiliary equipment has increased dramatically, causing significant direct and indirect losses to users. According to the actual application of a large number of users, this paper analyzes the causes of the above problems from the aspects of application environment, electromagnetic interference and anti-interference, power grid quality, motor insulation, etc., and puts forward some suggestions for improvement.
1. Work environment
In the actual application of frequency converter, except for a few special machine rooms, most domestic customers directly install the frequency converter on the industrial site to reduce costs. The working site is usually dusty, hot and humid in the south. There is also metal dust in the cable industry, corrosive gas and dust in ceramics, printing and dyeing and other industries, and explosion-proof requirements in coal mines and other places. Therefore, corresponding countermeasures must be made according to the site conditions.
1.1 Basic requirements for installation design of frequency converter
(1) The frequency converter shall be installed inside the control cabinet.

(2) The frequency converter is preferably installed in the middle of the control cabinet; The frequency converter shall be installed vertically, and the large components that may block the exhaust and inlet air shall be avoided to be installed directly above and below.

(3) The minimum distance between the upper and lower edges of the frequency converter and the top, bottom, or partition of the control cabinet, or large components that must be installed, should be greater than 300mm.

Basic requirements for frequency converter installed in cabinet

(4) If special users need to remove the keyboard during use, the keyboard hole on the inverter panel must be strictly sealed with tape or replaced with a false panel to prevent a large amount of dust from entering the inverter.

(5) The frequency converter shall be maintained regularly, and the internal dust shall be cleaned in time.

(6) Other basic installation and use requirements must comply with the relevant instructions in the user manual; If you have any questions, please contact the technical support personnel of the corresponding manufacturer in time.
1.2 Design requirements for dust control cabinet
It is necessary to take correct and reasonable protective measures when using frequency converters in dusty places, especially in places with polymetallic dust and flocs. Proper dust prevention measures are very important to ensure the normal operation of frequency converters. Generally, the control cabinet shall be sealed as a whole and ventilated through specially designed air inlet and outlet; The top of the control cabinet shall be equipped with protective screen and protective top cover air outlet; The bottom of the control cabinet shall be equipped with a base plate, an air inlet and an inlet hole, and a dust screen shall be installed.
(1) The air duct of the control cabinet shall be reasonably designed, and the air exhaust shall be smooth to avoid eddy currents in the cabinet and dust accumulation at fixed positions.

(2) A protective top cover shall be installed above the air outlet at the top of the control cabinet to prevent debris from falling directly into it; The height of the protective top cover shall be reasonable without affecting the ventilation. Protective mesh shall be installed at the side air outlet of the protective top cover to prevent flocculent debris from falling directly into it.

(3) If the side exhaust mode at the top of the control cabinet is adopted, the air outlet must be installed with protective mesh.

(4) Make sure that the axial flow fan at the top of the control cabinet rotates in the correct direction to extract air. If the fan is installed outside the top of the control cabinet, ensure that there is sufficient height between the protective top cover and the fan; If the fan is installed inside the top of the control cabinet, the bolts required for installation must be made of non-return elastic parts to prevent the fan from falling off and causing damage to the components and equipment in the cabinet. 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) The front, back and other joints of the control cabinet shall be sealed with sealing gasket or sealant to prevent dust from entering.

(6) All air inlets and wire inlets at the bottom and side panels of the control cabinet must be equipped with dust screens. Prevent the entry of flocculent sundries. The dust screen shall be designed to be removable for easy cleaning and maintenance. The mesh of dust-proof net shall be small, which can effectively block small flocs (similar to the mesh of ordinary household mosquito and fly screens); Or determine the appropriate grid size according to the specific situation. The junction between the dust screen and the control cabinet shall be treated strictly.

(7) The control cabinet must be maintained regularly, and the internal and external dust, fuzz and other sundries must be cleaned in time. The maintenance cycle can be determined according to the specific situation, but should be less than 2-3 months; For places with serious dust, it is recommended that the maintenance period be about one month.