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In our post What Do NEMA Sizes Mean?, we examined the NEMA frame sizes in which step motors are made. Larger frame sizes produce more torque. But this is not a one dimensional process: within a given frame size, the motor length can vary and that also affects torque. Because step motors require expensive tooling in order to be produced economically, a fixed rotor length is chosen, as is the stator that surrounds it.

Step motors are categorized by frame size, such as "size 11" or "size 23".  Ever wonder how that came to be or what it means?  The National Electrical Manufacturers Association sets standards for many electrical products, including step motors.  Generally speaking, "size 11" mean the mounting face of the motor is 1.1 inches square.

If you are new to step motors, you may be wondering how to mount one in your application. You’ll need to be concerned with three things: piloting the motor, fastening it to the mounting surface, and coupling the shaft to your load.

Background In some applications, power dissipation in step motors and drives  is a critical aspect of system design. Too much heat from the drive can cause a cabinet to overheat. Too much power loss in the motor can cause the motor to overheat at high ambient temperatures. Heat can also transfer into attached equipment causing it to misbehave. One example is a digital ink pump, where excess heat from the motor can cause undesirable changes in the viscosity of the ink. A recent customer was modeling their enclosure and requested detailed power dissipation data.