Design considerations for variable frequency control cabinets

 1、 Heat dissipation issues

The heating of Guangxi frequency converters is caused by internal losses. The main circuit accounts for about 98% of the losses in various parts of the frequency converter, while the control circuit accounts for 2%. In order to ensure the normal and reliable operation of the frequency converter, it is necessary to dissipate heat. We usually use a fan for heat dissipation; The built-in fan of the frequency converter can take away the internal heat dissipation of the frequency converter box. If the fan cannot work properly, the frequency converter should be stopped immediately; A high-power frequency converter also needs to add a fan to the control cabinet, and the air ducts of the control cabinet should be designed reasonably. All air intakes should be equipped with dust nets, and the exhaust should be unobstructed to avoid the formation of eddy currents in the cabinet and the accumulation of dust in fixed positions; Choose the matching fan according to the ventilation volume specified in the frequency converter manual, and pay attention to vibration prevention during fan installation.

2、 Electromagnetic interference issues

1. During the operation of the frequency converter, due to rectification and frequency conversion, a lot of interference electromagnetic waves are generated around it. These high-frequency electromagnetic waves have a certain degree of interference with nearby instruments and meters, and will generate high-order harmonics. These high-order harmonics will enter the entire power supply network through the power supply circuit, thereby affecting other instruments. If the power of the frequency converter is large and accounts for more than 25% of the entire system, it is necessary to consider anti-interference measures for controlling the power supply.

2. When there are high-frequency impact loads such as welding machines and electroplating power supplies in the system, the frequency converter itself may be protected due to interference, so the power quality of the entire system should be considered.

3、 The following points need to be noted for protection issues

1. Waterproof and anti condensation: If the frequency converter is placed on site, it should be noted that there are no pipeline flanges or other leakage points above the frequency converter cabinet, and there should be no splashing water near the frequency converter. In short, the on-site cabinet protection level should be IP43 or above.

2. Dust prevention: All air intakes should be equipped with dust nets to block the entry of flocculent debris. The dust nets should be designed as detachable for easy cleaning and maintenance. The mesh of the dust-proof net shall be determined according to the specific situation on site, and the junction between the dust-proof net and the control cabinet shall be treated tightly around it.

3. Anti corrosive gas: This situation is more common in the chemical industry, and in this case, the frequency converter cabinet can be placed in the control room.

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