AC Motor Frame Type

Every motor has been manufactured to specifications that are identified as a frame size. Fig. 1 shows a table with frame size data. These data include the distance between mounting holes in the base of the motor, the height of the shaft, and other critical data about physical dimensions. These data are then given a number such as 56. The frame number indicates that any motor that has the same frame number will have the same dimensions even though it may be made by a different company. This allows users to stock motors from more than one manufacturer or replace a motor with any other with the same frame information with confidence that it will be an exact replacement.

Above: Fig. 1: NEMA frame dimensions table for physical sizes for motors. Click here or image for print-quality size.