Siemens induction motors- generators cgii User Manual

 

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Angular Alignment 
Hold each shaft at maximum end float.  Rotate both 
shafts together, and measure between matching points 
at the outside diameter of the coupling faces for the 
top, bottom and both sides.  Use two indicators 
because of possible axial shaft movement.  Read 
difference of variation between them. 
 
Align shafts so that the total indicator variation does 
not exceed 0.002 inch.  (See Figure 1.) 
 

 

Figure 1.  Diagrams Showing Parallel and 

Angular Misalignment

 

 

Foot Plane 
The proper foot plane exists when adequate shims 
have been installed to assure equal pressure on each 
foot or corner of motor when the mounting bolts are 
loose. 

 

To determine proper foot plane: 
1.  Mount dial indicator on shaft to be checked so that 

contact will rest on either the adjacent shaft or a 
bracket from the foundation or base. 

2.  With mounting bolts tight and indicator set at zero, 

release one bolt at the shaft extension end of the 
unit and check indicator for a maximum change    
of 0.001 inch. 

 
3.  If no change is indicated, retighten the bolt and 

repeat the process for each of the remaining three 
mounting bolts. 

4.  If a change is indicated, add shims under motor 

foot and retighten until indicator movement is 
reduced or eliminated. 

 

1.  The foot plane is of concern for each unit of rotating 

equipment. Check driven equipment if necessary. 

2. Base or foundation rigidity can also affect vibration; 

check for resonance in supporting structure. 

3.  Recheck alignment after any change in shims and 

document alignment readings for warranty information. 

 
V-Belts 
Check belt manufacturer’s recommendations for 
maximum speed of sheaves and belts, minimum pitch 
diameters, maximum allowable number of belts and 
maximum sheave width. 
 
When motor is ordered for V-belt drive, check motor 
outline for motor manufacturer’s limits on belt pull, 
sheave distance from motor, and sheave diameter. 
 
Use only matched-belt sets.  V-grooves must be in line; 
sheaves must be parallel and axially aligned.  Belts 
must enter and leave sheaves with no side bending.  
For long bearing life, the belt tension is important; 
consult belt manufacturer for proper tension to suit 
drive.  Protect belts from grease and oil.  NEVER use 
belt dressing. 
 

It is possible for the motor shaft height to change 
relative to the driven equipment and this should be 
compensated for during the alignment procedure.  
Heat from driven equipment can also cause horizontal 
misalignment. 
 

Rotating parts. 
Can cause serious injury. 
Disconnect and lock out power before working on 
equipment. 

 
If motor application is abnormal (high temperature, 
extreme vibration, etc.) consult the factory for special 
instructions or additional information. 
 

If vibration levels increase cold to hot, alignment should 
be checked hot to verify that motor and driven equipment 
are properly aligned at operating temperature.  Adjust if 
necessary.