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Matters needing attention in the application of frequency converters for cattle house fans

In recent years,Cowshed fanIn the actual engineering application, for the variable-speed use of the speed-adjustable fan, the voltage-regulation and speed-regulation application of the single-phase asynchronous motor has gradually changed to the frequency-variable speed-regulation application of the three-phase asynchronous motor. Three-phase asynchronous motors have many advantages in using inverter speed regulation. It should be noted that the power factor of the motor in actual operation can be improved. It is more energy-saving at low speed operation, and the fan speed is more accurate. The cost is relatively low. However, due to the independence of the frequency converter's speed regulation principle, it should be noted that the output uses high-frequency carrier modulation. In actual use, if it is not used properly, some inexplicable failures and problems often occur, even causing damage to the fan motor. Due to space limitations, this article only provides some suggestions for the problems that need to be paid attention to in practical applications, and does not involve the related motor drag and inverter theory and principles.

  1. When the inverter is used for the frequency conversion fan, the lower frequency should not be lower than 30 HZ, and the low frequency limit must be set in the inverter. When the fan is at 30 HZ or 60% speed, the 25 Pa air volume is usually 35%-40% of the air volume under {Z5}} HZ full speed operation, basically Can meet the demand, the specific air volume data can refer to the fan manufacturer's fan frequency conversion speed control test data. When the air volume under 30 HZ still cannot meet the requirements, it is necessary to replace the fan with a smaller air volume. Generally, the livestock farm cattle fan is equipped with an asynchronous motor with insulation class F class. It will not cause problems when used above 30 HZ, but when used below 30 HZ will reduce the life of the motor and even run at a lower frequency The motor will be damaged quickly.

  2. The frequency converter should be as close as possible to the fan to reduce the cable length. When one-to-one (one inverter drives only one fan motor) is applied, and the cable length exceeds 50 m, the output reactor must be added at the output of the inverter, otherwise the motor will be easily burned. When more than one drive (one inverter drives multiple livestock husbandry fan motors simultaneously), and the cable length to any one motor exceeds 30 meters, the output reactance must be increased at the output end of the inverter Otherwise, it is easy to burn the motor.