Abstract: Variable speed AC motors are selected in accordance with user defined characteristics. A reference database containing information on a selected variety of frame/modules is modified in accordance with selected input data. The complexity of selecting an appropriate sized frame/module is simplified by utilizing key information about the motor electromagnetic characteristics as well as how they will vary due to operation at some user/application-defined operating conditions. The user/application-defined operating conditions are multi-dimensional, and include cooling/enclosure variations, ambient temperature, altitude, service factor, minimum, nominal, and maximum speeds (and corresponding continuous and momentary load torques at each of these speeds). This allows a person without intimate knowledge of motor characteristics to choose an optimal combination of motor and corresponding variable voltage, variable frequency supply for a particular application.