8.Noise
8.1 Noise be measured based upon JEM 1020
Microphone be placed 1 meter from the motor at the same height of its shaft.
Make 4 measurements around the motor , and take the average of the obtained values as the noise level.
A-scale be adopted for noise compensation circuit.
8.2 Reflexion from the surrounding (room coefficient) and noise from the surrounding
Noise measuring should be conducted in the surrounding with minimum reflexion . In a concrete building , space of the room , facilities in the room and the relative positions of machines contribute a great deal to reflexion , which , in turn , influence the measured noise level . Therefore , below the range of 3dB(A), the measured noise level may become louder than actual level.
When the noise level of the motor equals that of the driven machine , their result is augmented by 3dB; when the difference between them is 6dB, the higher level is augmented by 11dB; when the difference is 10dB, the higher level dominates. Should corrective steps be taken , machine with higher noise level must be adjusted first.
Check points for routine maintenance
| Part To Be Checked | Period Of Check | Itemes To Be Checked | Corrective Steps | |
| Motor Frame | Annually | vibration | Vibration meter, Feeling | Find out the cause of abnormal vibration and corrective steps taken. |
| Annually | Noise | Hearing, Stethoscopic rod | Make a survey of the site. | |
| Annually | Temperature of frame | Feeling or Thermometer | Check power source, load and dust accumulated on fins. Correction be made. | |
| Annually | Dirt on the frame | ¡@ | ¡@ | |
| Annually | Ventilation | Temperature of circulating air, by feeling or thermometer | Check and see wheather the inlet and outlet of air are
blocked. Clean the blinds, air nets and air filters. |
|
| Power Source | Annually | Voltage & current | Electrical measuring meters | Check and see wheather there is any change of the rated value. |
| Bearing | Annually | Sound from bearings | Stethoscopic rod | Grease be supplied and removed as
prescribed on nameplate Surface layer and color of the oil. Look up 6.1, 6.2 and 6.3 for information . |
| Annually | Temperature of bearings | Thermometer | ||
| Annually | Vibration of bearings | Feeling or Vibration meter | ||
| Timely | Discharged grease | Color, hardness and foreign bodies. | ||
| Annually | Oil leakage | ¡@ | ||
| Inside The Motor | Every 6 Months |
Mega ohm of windings | Megger | Periodic cleaning. |
| Annually | Bad odor | Open type machine | ||
| Annually | Dirt | Dust, foreign bodies and water. | ||
| Others | Annually | Coupling status | Coupling device , belts ougears. | Stop the motor for checking. |
| Annually | Protctive device | Make sure they are in serviceable condition. | ||
| Annually | Fastening device | Foot-fastening bolts and other fasteners. | ||
The structure of 3£r induction Motor. Squirrel Cage. Rotor , Enclosed-Ventilated type
| 1.Bearing bracket | 8.Fastening bolts for air guiding plate | 15.Shaft hole sealing device | 22.Preload spring |
| 2.Fastening bolt for bracket | 9.Fastening bolts for bracket | 16.Rotor fastening key | 23.Air-guiding plate |
| 3.Fastening bolts for air guiding plate | 10.Bearing bracket | 17.Rotor core, end-ring & vanes | 24.Terminal plate |
| 4.Eye bolt | 11.Air guiding plate | 18.C-clamp | 25.Terminal cover |
| 5.Frame | 12.Key at shaft-end | 19.Shaft hole sealing device | 26.Terminal cover |
| 6.Stator core | 13.Shaft | 20.Ball bearing, sealed type | 27.Terminal fastening bolts |
| 7.Stator winding | 14.Ball bearing, sealed type | 21.Duster | 28.Terminal box |
The structure of 3£r Induction Motor. Squirrel Cage Rotor Totally-Enclosed Fan-Cooled
| 1.Eye bolt | 9.Bearing | 17.Inner bearing-cap | 25.Outer bearing bracket |
| 2.Stator core | 10.Key at shaftend | 18.Bearing | 26.Bracket |
| 3.T-box | 11.Shaft | 19.Lock nut | 27.Grease nipple |
| 4.Fastening bolts for bracket | 12.Lock nut | 20.Fastener for fan | 28.Fastener for fan hood |
| 5.bracket | 13.Fasteners for inner bearing cap | 21.Hexagonal head bolts | 29.Inner fan |
| 6.Inner bearing cap | 14.Grease outlet | 22.Lock-washer | 30.Fastening ring |
| 7.Greasing Pipe | 15.Fastener for outlet cover | 23.Fan hood | 31.Stator winding |
| 8.Outer bearing cap | 16.Rotor core. end ring | 24.Outer bearing bracket | 32.Frame |
Check on receipt | Installation | Means of coupling | Running | Maintenance | Bearing maintenance | Vibration | Noise | back