Method for identifying motor noise
Method for identifying motor noise
Power outage method
By utilizing the characteristic of electromagnetic noise changing with the strength of the magnetic field, the magnitude of the current, and the level of conversion, if a motor running under no-load suddenly loses power and the noise disappears immediately, this is electromagnetic noise; If the motor continues to operate under inertia without significant improvement in noise after power failure, it is considered mechanical noise.
Change voltage method
When the power supply voltage drops rapidly to a certain limit (but the speed should not change significantly), if there is electromagnetic noise, it will be significantly affected by the voltage change, while other noises remain basically unchanged.
Current testing method
If the stator winding is asymmetric or has internal phase failure, inter turn faults, etc., the three-phase current will be unbalanced; If the rotor bar is broken or the winding rotor is three-phase asymmetric, the stator current fluctuates, which can be determined as electromagnetic noise.
Dragging method
Use a low-noise motor to drive the test motor to rotate. If it is a wound rotor motor, the carbon brush noise factor can be eliminated by lifting and lowering the carbon brush.
Disassembly method
The stable characteristics of aerodynamic noise can be identified by the changes in noise before and after removing the fan (small motor) or external blower (large or medium-sized motor). In addition, replacing fans with different outer diameters and types can distinguish the difference in noise at different speeds and also identify fan noise.
