First, let us take a brief look at the modern accelerometers in general.

They are divided into two main types: piezoelectric and MEMS (microelectromechanical systems). The first type is a time-proven device with a wide frequency range that can measure big acceleration values. The second is a modern device with a narrow frequency range (usually up to 3 or 4 kHz), with the purpose of measuring low frequencies.

How to Choose an Accelerometer — microelectromechanical systemsHow to Choose an Accelerometer — piezoelectric accelerometers

The piezoelectric accelerometers also have two distinguished types: IEPE and charge

IEPE accelerometers have become the most commonly used in recent years. Simply put, an IEPE accelerometer is a piezoelectric accelerometer with a built-in microelectronic charge amplifier that converts electrostatic charge from the piezoelectric element into a voltage signal. The IEPE accelerometer requires a power supply to operate, usually from 4 to 20 mA. The IEPE accelerometer is resistant to electric disturbances and does not require special low noise cables.

Charge piezoelectric accelerometers are less popular nowadays because they require an external charge-to-voltage converter. However, the charge accelerometer has some advantages, e.g. high operation temperature and an extremely wide amplitude range. A typical charge accelerometer can function in the temperature range from –55˚C to 288˚C.

There are two distinct groups of accelerometers based on the number of axes: one and three sensitivity axes. Only triaxial accelerometers can measure vibration along X, Y and Z axes simultaneously.

How to Choose an Accelerometer — three-axial accelerometers  How to Choose an Accelerometer — shock accelerometer

Moreover, there are accelerometers that are used for measuring high amplitude vibration — up to 10,000 g. They are usually small in size. 

Accelerometers have a number of other characteristics:

  • Sensitivity
  • Amplitude range
  • Frequency range

Accelerometers with bigger sensitivity are used to measure low-level vibrations and vice versa.

Before purchasing an accelerometer, try to answer the following questions: 

  • Which amplitudes of vibration do you need to measure? Is there a need to measure high vibrations and use shock accelerometers?
  • Which frequency range of vibration do you need to measure? Is it necessary to measure low frequencies and apply MEMS accelerometers?
  • Do you need to measure 3 axes simultaneously?
  • Does the measuring system have a charge amplifier? Does the measuring system have an IEPE power supply?

Regarding the RL-C21 and RL-C25 vibration systems, the best choice for a common vibration test will be an IEPE accelerometer with 10 mV/g sensitivity. However, you can easily connect a charge accelerometer, as both systems have an embedded charge amplifier.

The desired sensitivity for the transient capture tasks depends on the acceleration level. 10 mv/g or 10 pC/g sensors work well for low levels – 100-500 g. If the task requires you to measure the acceleration of 1,000 g or above, it will be better to use a sensor sensitivity of 1 mV/g or less.

If you have any doubt and don't know what accelerometer would be best for your task, contact our 24/7 technical support via email or call +371 6610 2166.