Noise:
Noise testing analyzes audible noise, generated by a motor, by doing a frequency analysis and comparing it to an envelope based on a median of setup motors. The analysis must have a certain percentage of data points fall within this envelope or the part will fail.

There are six different ranges available for noise - 1000 Hz, 2000 Hz, 3000Hz, 5000 Hz, 7000 Hz and 10,000.

Vibration & Resonance:
Resonance testing analyzes a combination of audible noise and vibration, generated by a motor, by doing a frequency analysis and comparing it to an envelope based on a median of setup motors. This method tests for resonance by making contact with the motor body and determines at which frequency and amplitude the motor is resonant. The resonant frequency is much larger than other frequencies generated within the motor. Resonance is processed the same as noise (FFT analysis) and uses the same ambient noise cancellation feature as developed by ESW for noise. Resonance is measured in Rones.

There are four ranges available for Resonance - 500 Hz, 1000 Hz, 2000 Hz and 3000 Hz.

Ambient Cancellation Technique:
ESW’s exclusive ambient cancellation testing technique identifies the ambient noise, resonance and vibration levels on the factory floor and then separates them from the noises, resonance's and vibrations created by the motor-under-test. This is done each time a motor is tested, allowing for ambient sampling on every motor.

Readings are taken before, during and after powering the motor. The FFT mathematical processing identifies all of the frequencies (both ambient and motor). Our customized software coupled with advanced data storage capabilities allow the ESW Test System to subtract out the ambient portion from the motor portion, data point by data point.

Noise, resonance and vibration data is stored individually into 30 different frequency bands ranging from 0-10,000 Hz. These frequency ranges are customized for each application. ESW also can analyze the data with our unique envelope analysis software.

There are three different methods that can be used to collect information from the motor. A thorough evaluation of your motors will determine which is the best method or combination of methods for your particular application/process.

Resonance Acoustic Probe:
The vibration data is collected using an “Exclusive” Resonance Acoustic Probe specially designed by ESW. This unique probe breaks up air movements and ambient noises into white noise. The sound channels used are specifically designed for the motor-under-test. A combination of highly repeatable transducers and ESW's Noise Cancellation Software eliminates 90% - 95% of ambient factory noise and vibrations.

The Resonance Acoustic Probe converts mechanical movement from the motor and motor casing into sounds. The diaphragm controls the movement of air (the vibration) down the chamber into the collection device. The tester is then able to look at the frequencies generated by the movement of the motor before these noises and vibrations are dispersed into the air. This probe eliminates the contamination of other frequencies that could have been picked up along the way. Only the true readings are displayed.

The Resonance Acoustic Probe is equipped with ESW’s exclusive spring-loaded constant pressure transducer. This transducer was developed exclusively for noise & vibration analysis and is highly repeatable. Special emphasis is placed on the location of these transducers. The transducer’s position is isolated from the holder (transducer) and the motor test fixture to ensure that the vibration picked up is from the motor.

Microphone:
The use of microphones (even high-end products costing thousands of dollars) will not guarantee you get “good” broadband frequency data. In fact, higher-end microphones also pick up movements and ambient conditions, resulting in poorer data.

Our microphones are commercially available and are selected based upon the application. The key to our success is how we channel the motor noise into the microphone.

Accelerometer:
ESW uses a variety of proven, commercially available accelerometers. Our goal is to detect only the vibrations transferred from the motors. Extra care is taken to determine the strategic placement.