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Machine Health Monitoring provides efficient methods by reducing downtime and preserving assets. Vibration monitoring will enable preventive maintenance on almost any type of machine. It could be done by recurrent control or real time analysis. Condition monitoring involves fixing sensors to mechanical parts of the machines in order to track failures and malfunctions.

 

Components Monitored Possible Faults Frequency Range
Support structure Imbalance, external vibrations, oil-whirl DC 0 Hz – 100 Hz
Shaft, gear, slide-bearing Imbalance, hunting mesh, misalignment, looseness DC 0 Hz – 1’000 Hz
Gear, bearing Mesh faults, gear pitting, shocks 100 – 10’000 Hz
Bearing, motor Acoustic vibrations 10’000 – 100’000 Hz

 

Low frequency monitoring (from DC 0 Hz to 1000 Hz) includes:

•    Hunting tooth detection
•    Low speed fan monitoring in cooling towers
•    Low speed agitators in industries
•    Geophysical measurement equipment

Explanation of the System

MHM will be set up according to the type of faults to analyze, by measuring frequency ranges. In general, spectrum analysis is used to identify the different vibration frequencies.

machine health monitoring schematics

Environment Analysis

MHM requires reliable sensors, resistant to possibly high temperature and repetitive shocks. The system must be able to operate in wet and corrosive environments (e.g. in a cooling tower). Furthermore, the sensors must last as long as the component analyzed.

MHM Conditions

Monitoring at low frequencies implies two major requirements. First of all, the noise produced by the sensor must be as low as possible: the least amount of electronic noise generated, the quicker a fault is detected. As an example, specific CNC machines require sensors with a noise level between 75 and 90 dB, operating at a low frequency (DC 0 Hz – 1’000 Hz). Secondly, a high voltage output is key to set a sufficient threshold.

Sensors Recommended

The vibration sensors are accommodated for this application, particularly the VS1000 series. The good ranges of measurement would be ±2g, ±5g and ±10g. The VS1002 sensor’s property is its very low noise level of 7 µg/√Hz – equivalent to class C at 90 dB. The VS1000 sensors have a non-linearity of 0.1% (typ. full scale), a linear frequency response from DC 0 Hz to 2500 Hz at ±5% FS, up to 7000 Hz at -3 dB. A maximum shock resistance of 6000g ensure a strong survivability of the sensors.

Recommended Sensor

VS1000

We recommend the VS1000 for Machine Health Monitoring application.

More about the VS1000

Full Application Note

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Application Note PDF