Note for frequency inverter selection

- Jul 25, 2019-

When selecting a universal drive, you should be aware of the following two points:

1 When the actual load of the motor is more than the rated output power of the motor, it is generally considered that the capacity of the inverter is selected to match the actual load. However, for general purpose drives, this is not ideal for the following reasons:

1) The motor also flows through the rated current 30% to 50% of the excitation current when it is not loaded.

2) The starting current flowing during start-up corresponds to the voltage and frequency applied by the motor, independent of the torque of the load. If the drive capacity is small and this current exceeds the overcurrent capacity, it is often not started.

3) The motor capacity is large, the motor leakage percentage is reduced by the inverter capacity as the reference, the pulsation of the inverter output current increases, so the overcurrent protection is easy to move, the motor often can not run.

2 When the motor starts with a universal inverter, the starting torque is mostly smaller than the starting of the labor frequency power supply, and sometimes cannot be started according to the starting torque characteristics of the load.