The Simple Method of Determining Motor Noise

Date: 2022-01-13     From: Longding     Author: admin

The motors are usually used in conjunction with mechanical equipment and are a common power source. However, even a motor with good performance can emit noise during operation. These mechanical noises can affect the performance of equipment, especially for precision machinery. To reduce noise, the following provides several methods for identifying the source of motor noise in the absence of dedicated noise measurement equipment.

The simple method of determining motor noise

1. Turn off the power

Using the characteristics of electromagnetic noise that changes with the strength of the magnetic field, the size of the load current and the level of the speed, the power is suddenly cut off after listening to the motor running at no-load for a period of time. With the power cut off, part of the noise will disappear immediately, this is electromagnetic noise. After a power failure, the noise generated by the motor continuing to run by inertia is mechanical noise. Repeat several times to obtain a determined noise source.

2. Change the voltage

Taking advantage of the characteristic that electromagnetic noise changes with the magnitude of the current, the power supply voltage is rapidly dropped to a certain limit (there is no major change in the rotational speed). If the electromagnetic noise is the main part of the motor noise, it will vary greatly with the voltage, while other noises are basically unchanged. This method is very practical for high-voltage starting and normal-pressure motors. If the motor is converted from voltage to normal voltage after synchronization, the part where the motor noise is significantly reduced is electromagnetic noise. If the motor noise does not change significantly, the noise generated by the motor is mainly other noise.

3. Current test

If the stator winding is asymmetrical or the internal phase is broken, or the inter-turn short circuit, the three-phase current is unbalanced. If the rotor cage is broken or the three-phase winding of the wound rotor is asymmetrical, the stator current fluctuates, so as to identify electromagnetic noise.

4. Drive method

The low-noise motor drives the motor under test to rotate, and the brushes are lifted and lowered several times to identify the impact of the brushes on noise. The aerodynamic noise has stable characteristics, which can be identified by the noise change before and after removing the fan or external blower. In addition, by replacing fans with different outer diameters and types, the difference in noise can be distinguished at different speeds, and aerodynamic noise can also be distinguished.