For motors of the same power, under the same workload conditions, high-speed motors have a smaller load but run faster, while low-speed motors have a larger load but run slower. However, within the same period of time, if the efficiency of the motors is comparable, the overall effect of the work done by both is the same. The choice between a high-speed motor and a low-speed motor depends on the actual application requirements of the working conditions.
Taking a three-phase asynchronous motor as an example, for two motors of the same power, a 2-pole motor and a 10-pole motor, their synchronous speeds are 3000 revolutions per minute and 600 revolutions per minute respectively. The diameters of the shafts of the two motors differ significantly. The shaft extension diameter of the low-speed motor is larger, and the corresponding torque is also greater.
In the actual testing process of motors, the starting and braking of high-speed motors are relatively easy, while those of low-speed motors are relatively more difficult.
From the visual parameter comparison of the two types of motors, the no-load current of high-speed motors accounts for a relatively small proportion of the rated current. For example, the no-load current of a 2-pole motor is approximately one-third of the rated current, while the no-load current of low-speed motors, in comparison to the rated current, mostly exceeds one-half or even higher.
Given these differences, under the same center height condition, the bearings used for high-speed motors and low-speed motors are also quite different. The bearing specifications for high-speed motors are relatively smaller; from the analysis of the bearing clearance, the bearing clearance for high-speed motors should be selected to be larger, while for low-speed motors, the basic group is more reasonable for the bearing clearance.
Post time: Nov-13-2025