NEMA Motor
These pages should be merged such that both pages do not attempt to cover the duplicate topics.
A "NEMA 24" StepperMotor is 2.4 inch by 2.4 inch.
NEMA is a US based association that attempts to set standards for manufacturing. For stepper motors, they have chosen a label that lists the size first. So a "NEMA 17" has a 1.7 inch by 1.7 inch faceplate. Any NEMA 17 motor will mount in the same mount holes of another NEMA 17. This gives the manufacturers more flexibility with their designs because they don't have to redesign the motor mount method just because they changed motor supplier.
If you want a really boring read, go to the NEMA website, then go into standards, search for motor. In the search results there should be a tabel of contents or an index for motors and generators. Read through it until you find the listing for motor labeling, look to the right of that listing and it will tell you what standard(s) you need to look for, then go to the standard(s) and start reading. If you make it past 5 pages before falling asleep then you may want to seek out a mental health professional.
Long Version
ok, so here is a write up a did a few years ago for a hobby robotics group to cover the basics. Let me know if I need to add more details. If you want the design tables, you can download the standard for free from NEMA after you create an account (free) with them.
NEMA is short for "National Electrical Manufacturers Association". The standards that NEMA creates are developed by the manufacturers through a voluntary consensus to provide descriptions of how things should be. Essentially, it is the manufacturers all agreeing that an apple is an apple and that a pear is not an apple. This makes swapping components easier, because you know ahead of time that one NEMA 17 motor will fit into the mounts of another NEMA 17 without having to redesign anything
The NEMA standards for Stepper Motors are covered in NEMA ICS 16 (Motion/Position Control Motors, Controls, and Feedback Devices). The stepper motor NEMA nameplate information is covered in Section 4.3.1.1 of ICS 16. The NEMA stepper motor naming includes diameter DD (inches x 10), mount type MM (inches x 10), length LLL (inches x 10), phase current CCC (amps x 10), insulation class I, phase voltage VVV (rating x 10), steps SSS, and winding code W. The quantites are written without a decimal point and a dash (-) to separate mounting characteristics from other data.
So the full NEMA description of a stepper motor is written as: NEMA DDMMLLL-CCCIVVVSSSW
Examples of naming:
- a 3.4" diameter stepper moter is a NEMA 34
- a 3.4" diameter stepper motor with a flange is a NEMA 34D
- a 3.4" diameter stepper motor with a flange and face tapped holes is a NEMA 34CD
- a 3.4" diameter stepper motor that is 1.6 inches long with a flange is a NEMA 34D016
and the most obnoxious name of all is
- a 3.4" diameter stepper motor with a flange that is 1.6 inches long, has a phase current of 1.6 Amps, class B insulation, 5.3 phase voltage, 200 steps per revolution, and type A winding connection is a NEMA 34D016-016B053200A
For square stepper motors, the length of a side is used instead of the diameter. So a square stepper motor that is 1.7" long on a side would be a NEMA 17 cube.
On to the boring details.
Flange (D) or Face (C) or Face Flange (CD) A NEMA flange (D) is a flange on the end of the motor that has slots (not holes) in the flange to slide bolts through. The flange types are given by a Flange number from 17 to 56. Each flange has different values A NEMA face (C) has tapped holes in the face of the motor even spaced around a pitch circle. A NEMA face flange (CD) has a flange with holes through the outside of the flange to allow for mounting. Note that these are through holes and not the slots of the regular flange. The holes are even spaced around a pitch circle. For all three of them, With the NEMA standards all flanges are designed alike and all face mount holes are designed alike. So if you buy a NEMA stepper with a flange, any other NEMA stepper that is the same size with a flange will mount in its place without any problems. The same goes with the face mount and the face flange - the holes will be in the same place. The exact size and hole locations of each can be referenced in tables on the web, but just about every manufacturer gives you the details of the mount type, so I am not including it here.
Insulation Defines the maximum allowable operating temperature Class A is 221 F Class B is 266 F Class F is 311 F Class H is 356 F In the US, Class B is the most common type for 60 cycle motors. Internationally Class F is the most common type for 50 cycle motors. And generally speaking, going 10 degrees above the maximum temperature will reduce the motor life by half.
Winding Code Describes how many internal wires the external wires are connected to. Most stepper motors have 4 to 8 wires on the outside of the motor and on the inside of the motor those 4 to 8 wires are connected to 2 or more wires. Winding type A is two wires, type B is 3 wires, type C is 4 wires, type D is 5 wires, type E is 6 wires, and finally type F is eight connected.
Tolerances There are specific tolerances for each measurement listed and many, many details about each one. In general, the stated value is within +/- 0.01. So an inch may be 0.99 inches or 1.01 inches and 5 volts maybe 4.99 volts or 5.01 volts.
explanation by criswilson10 in
http://dev.forums.reprap.org/read.php?14,32120,32369
