What do Suffixes mean in NEMA std. Motor Frames?

Low voltage NEMA motors come in frame sizes ranging from 48 to 445. There are different suffixes to frame sizes which carry a wide meaning and can help one understand much about mechanical side of the motors.

“Under NEMA standards, dividing first 2 digits of the frame size provide the shaft height dimension of the motor or generator. For example, the motor with frame size 256 is 25/4 = 6.25”

The different suffixes for NEMA frames and their meanings are specified below;

1. A - Industrial direct-current machine.

2. B - Carbonator pump motors. (See NEMA MG1-1998, 18.270 – 18.281.)

3. C - Type C face mounting on drive end.

4. CH - Face mounting dimensions are different from those for the frame designator having the suffix letter “C”. (the letters “CH” are considered as one suffix and should not be separated.)

5. D - Type D flange mounting on drive end.

6. E - Shaft extension dimensions for elevator motors in frames larger than 326T frames.

7. F - C Face mounting on opposite drive end.

8. G - Gasoline pump motors. (See NEMA MG1 – 1009.18.91.)

9. H - Indicates a small machine having an “F” dimension larger than that of the same frame without the suffix letter “H”. (See NEMA MG1 – 1998, 4.4.1 and 4.5.1.)

10. HP or HPH - Type P flange-mounted, vertical solid-shaft motors having dimensions in accordance with NEMA MG 1- 1009, 18.252. (The letter “HP” and “HPH” are considered as one suffix and should not be separated.)

11. J - Jet pump motors. (See NEMA MG1-1009, 18.132.)

12. JM - Face-mounted, close-coupled pump motor having antifriction bearings and dimensions in accordance with Table 1 of MG1-1998, 18.250. (The letters “JM” are considered as one suffix and should not be separated.)

13. JP - Type C face-mounted, close-couple pump motor having anti-friction bearings and dimensions in accordance with Table 2 of MG1-1998, 18.250. (The letters “JP” are considered as one suffix and should not be separated.)

14. K - Sump pump motors. (See NEMA MG1-1998, 18.78.)

15. LP or LPH - Type P flange-mounted, vertical solid-shaft motors having dimensions in accordance with MG 1-1998, 18.251. (The letters “LP” and “LPH” are considered as one suffix and should not beseparated)

16. M - Oil burner motors (See NEMA MG1-1998, 18.106.)

17. N - Oil burner motors. (See NEMA MG1-1998, 18.106)

18. P or PH - Type P flange-mounted, vertical hollow-shaft motors having dimensions in accordance with NEMA MG 1-1998, 18.238.

19. R - Drive end tapered shaft extension having dimensions in accordance with NEMA MG1-1998, 4.4.2.

20. S - Standard short shaft for direct connection

21. T - Included as part of a frame designation for which standard dimensions have been established.

22. U - Previously used as part of a frame designation for which standard dimensions had been established.

23. V - Vertical mounting only.

24. VP - Type P flange-mounted, vertical solid-shaft motors having dimensions in accordance with NEMA MG 1-1998, 18.237. (The letters “VP” are considered as one suffix and should not be separated.

25. X - Wound-rotor crane motors with double shaft extension. (See NEMA MG 1-1998, 18.229 and 18.230)

26. Y - Special mounting dimensions. (Contact the manufacture for dimensions.)

27. Z - All mounting dimensions are standard except the shaft extension(s). It is also used to designate double shaft extension(s).

Important Note:

Manufacturers may use any letter preceding the frame number, but will have no reference to standard mounting dimensions.