12
11
9. Maintenance
1) Operating environment: The vibration tester is a precision instrument, so it should
strictly avoid collision, percussion, damp, strong electricity, magnetic field, oil and
dust.
2) Clean the housing: Alcohol and diluent will corrode the meter housing, especially
the LCD. So when cleaning the housing, gently wipe with a small amount of water.
10. Appendix
a. Table of machine vibration levels (ISO2372)
Note:
(1) Class I: small machines (electrical motors of up to 15kW); Class II: medium
size machines (electrical motors with 15 to 75kW output); Class III: large prime
machines (rigid and heavy foundations); Class IV: large prime machines (soft
foundations).
(2) A, B, C and D are vibration levels. A means Good, B means Satisfactory, C
means Not Satisfactory, D means Not Allowed. The measurement velocity RMS
value should be in the three orthogonal directions of the bearing housing.
Ⅰ
Ⅱ
Ⅲ
Ⅳ
A
B
C
D
A
B
C
D
C
D
A
B
C
D
A
B
11
.
2
18
28
45
1
.
8
2
.
8
4
.
5
7
.
1
0
.
28
0
.
45
0
.
71
1
.
12
Vibration severity
Vibration velocity
Examples of quality judgement
for separate classes of machines
b. Maximum allowable vibration of motors greater than 1HP (NEMA MG1-12.05)
3000
~
4000
1500 2999
~
1000 1499
~
≤
999
25.4
38.1
50.8
63.6
Rev (rpm)
Peak-peak shifting amplitude (μm)
Note: For AC motors, use the highest synchronous Rev. For DC motors, use the
maximum power Rev. For series and multipurpose motors, use the operating Rev.
c. Maximum allowable vibration of large induction motors (NEMA MG1-20.52)
≥
3000
1500 2999
~
1000 1499
~
≤
999
25.4
50.8
63.6
76.2
Rev (rpm)
Peak-peak shifting amplitude (μm)
The two standards are set by the National Electrical Manufacturers Association
(NEMA).
d. Formed winding squirrel-cage induction motors
50.8
38.1
25.4
63.6
50.8
25.4
720~1499
1500~2999
≥
3000
Synchronous
Rev (rpm)
Peak-peak shifting amplitude (μm)
Elastic support
Rigid support
The standard is set by the American Petroleum Institute (API).
UT311A/UT312A
User Manual
UT311A/UT312A
User Manual
