How to select different frequency converters for load? If there is a special frequency converter for load, the special frequency converter shall be selected. If there is no frequency converter, the general frequency converter can only be selected.
What are the three different load characteristics of the inverter? People often divide the load in practice into constant torque load, constant power load and fan and pump load.
Constant torque load:
The torque TL is not related to the speed n, and TL remains basically constant at any speed. For example, friction loads such as conveyor belts and mixers, potential energy loads such as elevators and cranes, all belong to constant torque loads.
When the inverter drives the load with constant torque, it needs to operate at a low speed and steady speed, so that the torque can be large enough and the overload capacity can be sufficient. Finally, heat dissipation of standard asynchronous motor shall be considered to prevent excessive temperature rise of motor.
Constant power load:
The torque of paper machine, uncoiler and other specifications is inversely proportional to the speed n. This is constant power load.
The load constant power property changes within a certain speed. When field weakening speed regulation, the maximum allowable output torque is inversely proportional to the speed, which is constant power speed regulation.
When the speed is very low, due to the limitation of mechanical strength, the load torque TL has a maximum value, so it will become a constant torque.
The minimum capacity of motor and frequency converter is when the range of constant power and constant torque of motor is the same as that of load.
Fan and pump load:
According to the manufacturer of Chuangtuo Electric Frequency Converter, with the reduction of the rotating speed of fans, pumps and other equipment, the torque decreases according to the square of the rotating speed, and the power is proportional to the third power of the speed. In case of power saving, the frequency converter shall be used to adjust the air volume and flow through speed regulation. Because the required power increases rapidly with the speed at high speed, the load of fans and pumps should not exceed the power frequency.
Post time: Dec-15-2022