Hi. Could anybody help me out by explaining what motor frame size means, and how to obtain it if the motor name plate doesnt have it? Thanks in advance
shaniel21;
It may not be readily apparent from the tables.
The frame size describes the motor physically without regard to the windings.
Two motors may have the same frame size and will have identical physical dimensions, but one may be 1HP/ 1750 RPM and the other 2 HP/ 3500 RPM. Different cooling types often have different frame sizes for the same HP.
Eg; An Open style motor of a given Speed and HP will have a different frame size than a Totaly Enclosed Fan Cooled motor.
Any more than that is covered very well in the link in clyde38's post.
yours
Put simply the Frame size of a motor relates to certain critical dimensions of the casing and mounting arrangement that have been universaly agreed upon and adopted by manufacturers. For instance shaft length and diameter, the width and depth of the mounting feet hole centers, the PCD of a mounting flange or face (if fitted). The shaft height and the shaft end to the foot mtg hole centers. The idea being that makers all manufacture motors to the same sizes and that a motor in a certain application can be interchanged between different makes. If you dont have a frame size stated on the name plate you need a dimensioned drawing of the frame size (usually you can get them from makers websites) and then measure the distances mentioned and cross reference until you can identify and recognise the size.
As I am in the UK I deal with IEC frames which use the distance from the center of the shaft to the base (assuming its foot mtd)in mm to designate the frame size i.e. 132 or 315.
This link will allow you to download drwings for NEMA and IEC frame size dimensions
