The inverter selection is divided into light load and heavy load selection. To put it simply, light load generally means that what the motor must drive is lighter and the torque is relatively small. Heavy load means that the driven thing is heavier and the torque is large. Like fans and pumps, the general choice for light load is light load. Of course, not all fans and pumps are light-loaded. Roots blowers are heavy-loaded, and slurry pumps are also heavy-loaded.

The nominal power of the same inverter under light load and heavy load is different, that is to say, if it is under heavy load, the rated power of the inverter will be smaller. The overload capacity of the light load inverter is 1.1 times the rated current for 1 minute, and the overload capacity of the heavy load inverter is 1.5 times the rated current for 1 minute. The specific light load and heavy load depend on the output load of the motor. Simply put, if there is often an overloaded working state, it can be considered as overloaded.

According to the standard, we should choose according to some related parameters such as the load curve provided by the equipment manufacturer. For example, some equipment with large inertia (such as paper dryer) has a small normal operating current, but it has high requirements and high power when it starts/acceleration/deceleration/emergency stop control. In this case, we must consider saving investment and ensuring start-stop operation. This requires comprehensive consideration of the overload capacity of the motor and the frequency conversion. The motor does not need to be large, but the frequency conversion must be at least two levels of the large motor.

Therefore, the selection should be based on some related parameters such as the load curve provided by the equipment manufacturer.