| ROTATING MACHINERY HAVING RIGID ROTORS |
|
Table 1-Vibration Severity Criteria
Recommended for General Machinery Turning from 600 to 12000 RPM
(Based on ISO IS 2372)
|
RMS Overall velocity Level Measured in 1000 Hz Bandwidth |
Vibration Severity Criteria
|
||||
|
Mm/s |
In/s |
Class I |
Class II |
Class III |
Class IV |
|
0.28 |
0.01 |
Good |
Good |
Good |
Good |
|
0.45 |
0.02 |
||||
|
0.71 |
0.03 |
||||
|
1.12 |
0.04 |
Satisfactory |
|||
|
1.8 |
0.07 |
Satisfactory |
|||
|
2.8 |
0.11 |
Unsatisfactory |
Satisfactory |
||
|
4.5 |
0.18 |
Unsatisfactory |
Satisfactory |
||
|
7.1 |
0.28 |
Unacceptable |
Unsatisfactory |
||
|
11.2 |
0.44 |
Unacceptable |
Unsatisfactory |
||
|
18 |
0.71 |
Unacceptable |
|||
|
28 |
1.10 |
Unacceptable |
|||
|
45 |
1.77 |
||||
Class I. Small-sized machines (powered from 0 to 15 KW)
Class II. Medium-sized machines (powered from 15 to 75 KW)
Class III. Large-sized machines (powered > 75 KW) mounted on "Rigid Support" structures and foundations
Class IV. Large-sized machines (powered >75 KW) mounted on "Flexible Support" structures
Note:
Support is determined as rigid support if the fundamental frequency of the machine installed on the support is higher than the machine main excitation frequency
Support is determined as flexible support if the fundamental frequency of the machine installed on the support is lower than the machine main excitation frequency
Table 2-Vibration Severity Criteria
Recommended for Slow Speed Large Machinery Turning from 600 to 1200 RPM
(Based on ISO IS 3945)
|
RMS Overall Velocity Level Measured in 1000 Hz Bandwidth |
Support Classification |
||
|
Mm/s |
In/sec |
Rigid Supports |
Flexible Supports |
|
0.46 |
0.018 |
Good |
Good |
|
0.71 |
0.028 |
||
|
1.12 |
0.044 |
||
|
1.80 |
0.071 |
||
|
2.80 |
0.110 |
Satisfactory |
|
|
4.60 |
0.180 |
Satisfactory |
|
|
7.10 |
0.280 |
Unsatisfactory |
|
|
11.2 |
0.440 |
Unsatisfactory |
|
|
18.0 |
0.710 |
Unacceptable |
|
|
28.0 |
1.100 |
Unacceptable |
|
|
46.0 |
1.800 |
||
|
71.0 |
2.800 |
||
ELECTRIC MOTOR
Table 3-Recommended Vibration Limits for Electric Motors
(Based on ISO IS 2373)
| Motor Grade | RPM | RMS Velocity amplitude for the following shaft heights, in mm | |||||
| 80 < h < 132 | 132 < h < 225 | 225 < h < 400 | |||||
| mm/s | in/s | mm/s | in/s | mm/s | in/s | ||
| Normal | 600 - 3600 | 1.80 | 0.071 | 2.8 | 0.110 | 4.5 | 0.177 |
| Reduced | 600 - 1800 | 0.71 | 0.028 | 1.12 | 0.044 | 1.8 | 0.071 |
| 1801 - 3600 | 1.12 | 0.044 | 1.80 | 0.071 | 2.8 | 0.110 | |
| Special | 600 - 1800 | 0.45 | 0.018 | 0.71 | 0.028 | 1.12 | 0.044 |
| 1801 - 3600 | 0.71 | 0.028 | 1.12 | 0.044 | 1.8 | 0.071 | |
Note:
- RMS velocity amplitude is measured in the frequency range from 10 to 1000 Hz.
- The shaft height is the vertical distance from the base of the motor to the centerline of the shaft
Table 4-Permissible Vibration for Large Induction Motors
(Based on NEMA MG 1-20.52)
| RPM | Displacement amplitude (peak to peak), in inch |
| 3000 - 4000 | 0.001 |
| 1500 - 2999 | 0.0015 |
| 1000 - 1499 | 0.002 |
| 999 and below | 0.0025 |
Motor vibration measurements should be carried out in the condition of motor no-load operation, at rated voltage and nominal frequency (AC motor), nominal speed(s), and motor operational temperature.
To determine vibration severity criteria for specific machineries or motor applications, please contact Vibratechnica at support@vibratechnica.com for support