Electric motors, ac motors and dc motors, come in many shapes and sizes. Some are standardized electric motors for general-purpose applications. 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.  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. Finalized electrical energy converted into mechanical energy