Once the load characteristic is determined, the converter capacity can be expressed by three parameters, i.e. converter power, rated current and maximum current. In the three electrical parameters, no matter which representation method, in the final analysis or the selection of the rated current of the frequency converter, it should be determined according to the actual situation according to the current that the motor may absorb from the frequency converter. Generally, there are two kinds of overload capacity of frequency converter: 1.2 times of rated current, lasting for 1min; 1.5 times of rated current, lasting for 1min.