Testing motor noise in an anechoic chamber is a systematic task that requires detailed planning and implementation from multiple perspectives. The following are the detailed steps for testing motor noise:

1. Preparation work
1.1 Inspection and calibration of anechoic chamber
Acoustic material inspection: Ensure that the sound-absorbing materials (such as sound-absorbing wedges, soundproofing cotton, etc.) in the anechoic chamber are intact and undamaged, without detachment or damage.
Background noise measurement: Use a sound level meter to measure the background noise level of the anechoic chamber, ensuring that it is at least 10 dB (A) lower than the noise of the motor being tested, to avoid the influence of background noise on the test results.
Equipment calibration: Calibrate all testing equipment (such as sound level meters, spectrum analyzers, etc.) to ensure that their measurement accuracy meets relevant standards.

1.2 Preparation of testing equipment
Sound level meter: Select a sound level meter that complies with national standards (such as GB/T 3785) and ensure that its sensitivity and frequency response meet the testing requirements.
Spectrum analyzer: Used to analyze the frequency components of noise, select a spectrum analyzer with sufficient resolution and dynamic range.
Data collection system: Prepare computers and related software for real-time collection and storage of test data.

1.3 Preparation of motor

Cleaning and inspection: Ensure that the surface of the motor is clean, free from oil stains, dust, or other debris.
Installation and fixation: Choose a suitable support frame or vibration damping pad according to the weight and size of the motor, ensuring that it is stably placed in the center position of the soundproof chamber.
Power supply and control: Connect the power supply and control equipment of the motor to ensure that it can start and operate normally.

2. Installation and positioning of motors

2.1 Selection of installation location

Central position: Place the motor in the center of the anechoic chamber, away from walls and other obstacles, to reduce the impact of reflected sound on the test results.
Support method: Choose an appropriate support method based on the weight and size of the motor. If the motor is heavy, it is recommended to use damping pads or suspension devices to prevent ground vibrations from affecting the test results.

2.2 Installation and fixation

Stability check: Ensure that the motor is installed securely and will not experience displacement or tipping due to vibration.
Vibration reduction measures: Place vibration reduction pads or use suspension devices at the bottom of the motor to reduce the impact of ground vibrations on test results.

3. Testing methods

3.1 Static testing method

Definition: Static testing method refers to measuring noise when the motor is stationary.
Operation steps:
Start the motor and keep it in a stationary state (without loading any load).
Measure the noise level at different positions such as 1 meter, 2 meters, and 3 meters away from the motor using a sound level meter.
Record the sound pressure level (dB (A)) and frequency components at each measurement point.
Advantages: Low cost and simple operation.
Disadvantage: It cannot fully reflect the noise situation of the motor during actual operation.

3.2 Dynamic testing method

Definition: Dynamic testing method refers to measuring noise while the motor is running.
Operation steps:
Start the motor and load it with appropriate loads (such as belts, gears, etc.) to keep it in normal operation.
Measure the noise level at different positions such as 1 meter, 2 meters, and 3 meters away from the motor using a sound level meter.
Use a spectrum analyzer to analyze the frequency components of noise and record the sound pressure level (dB (A)) at each frequency point.
Adjust the motor speed and load, and repeat the above measurement process.
Advantages: It can more accurately reflect the noise situation of the motor during actual operation.
Disadvantage: Requires more equipment and technical support.

4. Data collection and processing

4.1 Sound level measurement

Measurement point arrangement: Multiple measurement points (such as front, side, rear, etc.) are arranged in the soundproof room to comprehensively evaluate the noise radiation characteristics of the motor.
Measurement distance: Usually, distances such as 1 meter, 2 meters, and 3 meters are selected for measurement to evaluate the variation of noise with distance.
Measurement time: The duration of each measurement should not be less than 10 seconds to ensure the stability and representativeness of the data.

4.2 Spectrum analysis

Frequency range: Typically, the frequency range of 100 Hz to 10000 Hz is selected for analysis to cover the main frequency components of motor noise.
Resolution setting: Set the resolution of the spectrum analyzer according to testing requirements (such as 1/3 octave or 1/6 octave) to improve analysis accuracy.
Data recording: Record the sound pressure level (dB (A)) and noise power level (dB (SPL)) at each frequency point.

4.3 Data Processing

Background noise subtraction: Subtracting the influence of background noise from test data to obtain more accurate noise measurement results.
Data averaging: Average multiple measurement data to reduce the impact of accidental errors on test results.
Result comparison: Compare the test results with relevant standards or specified values to determine whether the noise performance of the motor meets the standards.

5. Result analysis and reporting

5.1 Noise level assessment
Sound pressure level analysis: Based on the measured sound pressure level data, evaluate the noise level of the motor under different operating conditions.
Frequency component analysis: Based on the frequency spectrum analysis results, determine the main frequency components and their distribution of motor noise.

5.2 Noise source localization

Noise source identification: By analyzing the frequency components and radiation characteristics of noise, identify the main noise sources of the motor (such as bearings, fans, stators, etc.).
Noise propagation path analysis: Analyze the propagation path of noise from the source to the receiving point, determine key propagation paths and influencing factors.

5.3 Improvement suggestions

Noise reduction measures: Based on the analysis of noise sources and propagation paths, propose corresponding noise reduction measures (such as optimizing bearing design, adding soundproof covers, improving fan blade shape, etc.).
Validation and optimization: Verify and optimize the proposed noise reduction measures to ensure their effectiveness and feasibility.

6. Precautions

6.1 Environmental Control

Temperature and humidity: Keep the temperature and humidity inside the soundproof room constant to avoid the influence of environmental changes on the test results.
Pressure control: Ensure stable pressure inside the soundproof chamber to avoid measurement errors caused by pressure fluctuations.

6.2 Equipment Maintenance

Regular calibration: Regularly calibrate and maintain testing equipment to ensure its measurement accuracy and stability.
Equipment update: Timely update and upgrade testing equipment according to technological development and testing needs.

6.3 Safe Operation

Personnel protection: When conducting tests in high noise environments, ensure that testers wear earplugs or other hearing protection devices.

Equipment safety: Avoid equipment damage or personnel injury caused by improper operation.