No-load current and load current are two different motor current states.

No-load current is the current value of the motor when running without load. In this case, the output power of the motor is 0, and it only needs to overcome some internal resistance, such as the friction resistance of the iron core and bearings. The current consumed by the motor is small, usually only 10%-30% of the rated current.

Load current is the current generated by the motor when it is carrying a load or output power. The current consumed by the motor is related to the load it bears, and usually increases as the load increases until it reaches the rated current required at the rated load. Under load current, the motor needs to generate enough torque to complete the required tasks, such as driving the load to rotate, providing mechanical energy, etc.

Therefore, when we select a motor, we need to consider the current status of the two motors. For some applications that require long-term operation, such as bearings, fans, pumps, etc., we need to choose motors with small no-load current, high efficiency, and mainly run within the design rated load range.

In practical applications, it is very important to determine the value of the no-load current, because it not only reflects the characteristics of the motor itself, but also reflects the quality and performance of the motor. When selecting a DC motor or designing a motor drive system, one of the important technical parameters is the motor's rated current and no-load current. You can select the appropriate power supply and controller based on these parameters to ensure that the motor can work stably and at the same time improve the motor's performance. efficiency and longevity.

It should be noted that the no-load current of the motor has nothing to do with the load, and load changes will not affect its size. Therefore, in practical applications, no-load current is often used to diagnose motor faults. For example, when the no-load current is obviously high, it may indicate that there are loop contacts, loose structures, open windings and other faults in the motor, which require repair or replacement of parts. In addition, the quality and life of the motor can also be inferred from the changes in no-load current. Under normal circumstances, the change range of no-load current should be as small as possible, which means that the motor design is reasonable, the operation is stable, and the service life is relatively long.

To sum up, no-load current is one of the important technical parameters of DC motors, and it is also one of the important basis for judging the performance, quality and life of the motor. When selecting or designing a motor, it is necessary to carefully calculate and measure the no-load current, and reasonably optimize the relevant parameters to improve the efficiency and stability of the motor.