The Electric Motors Reference Center, from Machine Design, is designed to provide design engineers with the information they need to specify or purchase electric motors including: AC motors, DC motors, stepper motors and servo motors. The Electric Motors 101 section includes reference information about the various types of electric motors and the selection criteria and requirements used for typical mechanical engineering applications. This section is split into the electric motor type: AC motors, DC motors, stepper motors and electrical drives. Electric Motors Articles will point you to recent application and product articles that have appeared recently in the pages of Machine Design magazine. Electric motors, both ac motors and dc motors, come in many shapes and sizes. Some electric motors are standardized versions for general-purpose applications. Other electric motors are intended for specific tasks. In any case, electric motors should be selected to satisfy the dynamic requirements of the machines on which they are applied without exceeding rated electric motor temperature. Thus, the first and most important step in electric motor selection is determining load characteristics — torque and speed versus time. Electric Motor selection is also based on mission goals, power available, and cost.