Frequency converter selection and capacity matching - News - Global IC Trade Starts Here.

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First, select the inverter according to the load characteristics

Second, when selecting the inverter, the actual motor current value should be used as the basis for the inverter selection. The rated power of the motor can only be used as a reference. Secondly, it should be fully considered that the output of the inverter contains higher harmonics, which will cause the power factor and efficiency of the motor to deteriorate.

3. If the inverter needs to run long cable, the inverter should be amplified by one gear or installed with output reactor at the output of the inverter.

4. When the inverter is used to control several motors in parallel, it is necessary to consider the total length of the cable from the inverter to the motor within the allowable range of the inverter.

5. For some special applications, such as high ambient temperature, high switching frequency, high altitude, etc., this will cause the inverter to derate, and the inverter needs to be enlarged for one gear.

6. When selecting a frequency converter for a high-speed motor, it should be slightly larger than the inverter of a normal motor.

7. When the inverter is used for a pole-changing motor, it should pay full attention to the capacity of the inverter so that its maximum rated current is below the rated output current of the inverter.

8. When the explosion-proof motor is driven, the inverter does not have an explosion-proof structure, and the inverter should be placed outside the hazardous area.

IX. When using the inverter to drive the gear reduction motor, the scope of use is restricted by the lubrication method of the rotating part of the gear. Do not exceed the maximum speed tolerance.

10. When the inverter drives the wound rotor asynchronous motor, most of the existing motors are used. It is prone to overcurrent tripping due to ripple current, so choose a converter that is slightly larger than the normal capacity.

11. When the inverter drives the synchronous motor, it reduces the output capacity by 10% to 20% compared with the commercial frequency power supply.

12. For the load with high torque fluctuation such as compressor and vibration machine and the peak load of hydraulic pump, it is necessary to understand the operation of power frequency and select the inverter with higher rated current than its maximum current.

13. When the inverter controls the Roots blower, because its starting current is very large, it must be noted that the inverter's capacity is large enough when selecting the inverter.

14. When selecting the inverter, be sure to check whether its protection level matches the situation on site.

15. Single-phase motors are not suitable for inverter drive.

If there is high reliability of the inverter body, and the inverter selection and capacity matching are not appropriate, the variable frequency speed control system can not achieve high reliability or even run, so how to ensure the normal frequency conversion adjustment system Run efficiently?

We want to ensure that the capacity of the inverter matches. First, according to the nature of the load, the inverter type is selected correctly. The general principle is what kind of inverter with the nature of the load characteristics.

(1) Constant torque production equipment - The load torque is basically constant within the speed regulation range. A frequency converter with constant torque performance should be selected. Its overload capacity is maintained at 150% of rated current for 1 minute.

(2) Square torque production equipment--In the speed regulation range, the load torque is proportional to the square of the speed, ie M∝n2, centrifugal fan, water pump is its typical representative. A frequency converter with M∝n2 characteristics has a small overload capability, and 110%-120% of rated current is overloaded for 1 minute.

(3) Constant power load production equipment - in the speed regulation range, the speed is low and the torque is large; the high speed and the small torque are small, that is, M? NC (constant). Typical equipment such as machine tools and winding mechanisms.