Limit of rank “N” is suitable for common motor. When the request is higher
than that in the table, limit can be gotten by dividing the limit of rank 'S' with
1.6 or multiples of 1.6.
Note:
(1)“Class I” is small motor ( power less than 15 kw). “Class II” is medium
motor (power between 15 ~75kw). “Class III” is high power motor (hard base).
“Class IIII”
is high power motor (stretch base).
(2)A,B,C,D are vibration Rank. “A” means good, “B” means satisfying, “C”
means not satisfying, “D” means forbidden. Vibration velocity should be taken
from the three perpendicular axes on the motor shell.
B. ISO/IS2373 Motor quality standard according as vibration velocity
Quality
rank
Rev (rpm)
Normal
Good ( R)
Excellent (S)
600~3600
600~1800
1800~3600
600~1800
1800~3600
H: high of shaft (mm)
Maximum vibration velocity (rms)
(mm/s)
80
＜
H
＜
132
4.5
1.8
2.8
1.12
1.8
1.8
0.71
1.12
0.45
0.71
2.8
1.12
1.8
0.71
1.12
132
＜
H
＜
225
225
＜
H
＜
40
0
C. Maximum vibration of motor that power larger than 1 horsepower.
(NEMA MG1-12.05)
Rev (rpm)
3000~4000
1500~2999
1000~1499
≤
999
25.4
38.1
50.8
63.6
Displacement
(P-P) (um)
For AC motor, rev is maximum synchronous rev. For DC motor, it is maximum
power rev. For motor in series, it is work rev.
D. Maximum vibration of high power induction drive motor.
(NEMA MG1-20.52)
National Electric Manufacturers Association (NEMA)
Establishes two standards above.
Rev (rpm)
≥
3000
1500~2999
1000~1499
≤
999
25.4
50.8
63.6
76.2
Displacement
(P-P) (um)
