1.1 Scope
This standard specifies the IM Code, a classification of types of construction, mounting arrangements and the terminal box position of rotating electrical machines.
Two systems of classification are provided as follows:
Code 1 (see Chapter 2): An alpha-numeric designation applicable to machines with end-shield bearing(s) and only one shaft extension.
Code 2 (see Chapter 3): An all-numeric designation applicable to a wider range of types of machines including types covered by Code 1.
The type of machine not covered by Code 2 should be fully described in words.
The relationship between Code 1 and Code 2 is given in annex A (Informative).
1.2 Definitions
For the purposes of this standard, the following definitions apply:
1.2.1
Type of construction
The arrangement of machine components with regard to fixings, bearing arrangement and shaft extension (see GB/T 2900.25).
1.2.2
Mounting arrangement
The orientation on site of the machine as the whole with regard to shaft alignment and position of fixings (see GB/T 2900.25).
1.2.3
Shaft extension
A portion of a shaft extending beyond an extreme bearing (see GB/T 2900.25).
NOTE: The bearing may be on the machine itself or be part of an assembly comprising a machine and (an) additional bearing(s).
1.2.4
Drive-end of a machine (D-end)
That end of the machine which accommodates the shaft end (see GB/T 2900.25).
NOTE: This is normally the driving end of a motor or the driven end of a generator.
Where for some machines the above definition is inadequate, the D-end is defined as follows:
a) Machine with two shaft extensions of different diameter: the end with the larger shaft diameter;
b) Machine with a cylindrical shaft extension and a conical shaft extension of the same diameter: the end with cylindrical shaft extension;
c) Machine with other arrangements: according to GB 1971 if applicable; otherwise by agreement.
NOTE: The outer diameter of a forged-on flange is taken to be the diameter of the shaft extension.
1.2.5
Non-drive end of the machine (N-end)
That end of the machine opposite to the drive end (see GB/T 2900.25).
