Vibration sensor amplifiers

Measuring amplifiers for vibration sensors and vibration monitoring

Measuring amplifiers for vibration sensors provide power supply and signal conditioning for piezoelectric vibration transducers and IEPE sensors. They make the measured vibration signals available for further analysis, machine monitoring or transmission to control and data acquisition systems.

IEPE vibration sensors require a constant-current supply. The actual AC voltage signal from the sensor is superimposed on a DC voltage. A suitable measuring amplifier provides the required sensor supply, separates the dynamic measurement signal from the supply voltage and conditions it for further processing.

Depending on the version, Althen measuring amplifiers offer additional functions such as adjustable gain, high-pass and low-pass filters, RMS and peak value calculation, as well as integration of acceleration into vibration velocity or displacement. Devices with limit monitoring, relay outputs and frequency analysis are also available for continuous machine monitoring.

In addition to conventional analogue outputs such as 0–10 V, 4–20 mA and AC signal outputs, the portfolio also includes digital solutions with RS-485, USB and industrial communication protocols such as Modbus, OPC UA and MQTT. This makes it possible to integrate existing IEPE sensors into modern PLC, condition monitoring, edge and IoT systems.

Flexible signal conditioning for vibration measurement and condition monitoring

Althen measuring amplifiers for vibration sensors support both conventional dynamic measurements and continuous condition monitoring of machines and systems.

What to consider when selecting a measuring amplifier for vibration sensors

1. Determine the sensor type and output signal
First, the measuring amplifier must be compatible with the vibration sensor being used. The devices in this category are designed especially for piezoelectric sensors with an IEPE output.

In addition to accelerometers, certain amplifiers can also be used with other IEPE-compatible sensors, such as dynamic force or pressure sensors and IEPE microphones.

2. Consider the IEPE sensor supply
IEPE sensors require a constant-current supply. When selecting the amplifier, it is therefore important to check whether the current and supply voltage of the measuring amplifier are compatible with the connected sensor.

Althen amplifiers provide this sensor supply directly, simplifying the measurement chain.

3. Determine the required vibration quantity
An accelerometer initially measures vibration acceleration. By integrating the measurement signal, additional vibration quantities can be determined:

• Vibration acceleration
• Vibration velocity
• Vibration displacement

Which quantity is relevant depends on the machine and the specific monitoring task.

4. Consider the application's frequency range
The required frequency range depends on the vibration phenomena to be investigated.

Lower frequency ranges are often relevant for general condition monitoring of rotating machinery. Bearing diagnostics and other dynamic investigations, on the other hand, may require significantly higher frequencies.

Measuring amplifiers with adjustable high-pass and low-pass filters allow targeted adaptation to the required frequency range.

5. Select time-domain or frequency analysis
For simple monitoring of the overall vibration level, parameters such as RMS, peak or peak-to-peak values are often sufficient.

If it is necessary to determine at which frequencies specific vibrations occur, frequency analysis is required. The VIB-M14, for example, provides FFT analysis with freely definable alarm ranges, enabling frequency-selective machine monitoring.

6. Select the required output signal
Depending on the amplifier, different output signals are available for further processing.

Typical options include:

• 0–10 V
• 4–20 mA
• AC signal output
• RS-485
• USB
• Digital network protocols

For conventional PLC integration, for example, a 4–20 mA signal is suitable. For vibration analysers or oscilloscopes, the dynamic AC signal may be required.

7. Consider integration with PLC, SCADA or IoT systems
If the vibration measurement is to be integrated into a higher-level monitoring system, the required communication interface must be considered.

Digital interface adapters can, for example, transmit vibration data via Modbus, OPC UA or MQTT. This allows existing analogue IEPE sensors to be integrated into modern automation, cloud and condition monitoring systems without replacing the sensor.

8. Define limit and alarm functions
Warning and alarm functions are particularly important for continuous machine monitoring.

Depending on the device, limit values can be defined and relays can be switched when they are exceeded. This makes it possible to trigger warning messages or automatically shut down machines in the event of critical vibration conditions.

9. Consider diagnostic functions
Monitoring the sensor connection increases operational reliability. Various measuring amplifiers can, for example, detect cable breaks or short circuits at the sensor.

In more complex monitoring systems, additional parameters such as crest factor, frequency spectra or other vibration metrics can also be evaluated.

10. Plan a single- or multi-channel system
Compact single-channel devices are available for individual measuring points. If several sensors need to be recorded simultaneously, modular amplifiers can be combined.

This also makes it possible to build larger multi-channel measurement systems for test benches, laboratory applications or machine monitoring.

11. Consider mounting and installation location
Compact amplifier modules for mounting on 35 mm DIN rails are available for industrial applications. Modular systems allow several measuring channels to be installed side by side in a space-saving configuration.

When making a selection, the available installation space, supply voltage, wiring and proximity to the sensor should also be considered.

Our technical expert team will be happy to support you in selecting the vibration sensor, IEPE supply, frequency range, signal conditioning and interface for your application. Contact our sales team

Typical applications for measuring amplifiers and vibration monitoring

Measuring amplifiers for vibration sensors are used wherever dynamic sensor signals need to be reliably conditioned, analysed or continuously monitored.

Typical applications include:

• Condition monitoring
• Condition monitoring of machines and systems
• Predictive maintenance
• Monitoring of rotating machinery
• Rolling bearing and bearing monitoring
• Pump monitoring
• Compressor monitoring
• Fans and blowers
• Centrifuges
• Agitators and mills
• Motors and drives
• Process monitoring
• Machine and plant engineering
• Test benches and test systems
• Quality control in production
• Vibration analysis in laboratories
• Dynamic force and pressure measurements with IEPE sensors
• Sound measurements with IEPE microphones
• PLC- and DCS-based machine monitoring
• SCADA and cloud monitoring
• IoT-based condition monitoring

Thanks to different amplifier, filter, analysis and interface functions, the devices can be used both for conventional measurement tasks and for continuous automated condition monitoring.