Designs are given code letters “IM” in the same manner as degrees of protection and coolants. The letters also indicate the design group, assembly variety and shaft end execution.
Survey 7 - Design category explanations (first figure)
1 Foot machine with end shields
2 Foot machines with end shields and end shield flange
3 Machines without feet with end shields and flange on one shield
4 Machines without feet with end shields, with casing flange
5 Machines without bearings
6 Machines with end shields and pillow blocks
7 Machines with pillow blocks (without and shields)
8 Vertical machines which are not covered by the categories IM 1 to IM 4
9 Specially constructed machines according to assembly type
Survey 8 - Shaft end type of rotating electrical machines (fourth figure)
0 Without shaft end
1 With a cylindrical shaft end
2 With two cylindrical shaft ends
3 With a conical shaft end
4 With two conical shaft ends
5 With a flange shaft end
6 With two flange shaft ends
7 With flange shaft end on the D-side and cylindrical shaft end on the N-side
8 All other types with shaft ends.
The most common design groups are IM 1001 and IM 3001. The assembly variety is indicated through two numbers. Assembly variety relates to the erection site of the machine regarding the shaft axle and holding elements.
Survey 9 - Frequent design categories