VIBRO transducers

Transducers are essential to be able to measure vibrations. The choice of the right type of sensor is just as essential.

Bearing housing vibrations

bearing housing vibrations

These vibrations are measured on each bearing housing, according to the ISO 10816 standard in three directions: horizontal, vertical and axial. The quantity is vibration speed in mm/s rms.

There are two types of transducers that measure vibrations, namely acceleration transducers and vibration velocity transducers.

Accelerometers are the most universal, cheap to manufacture and have a wide frequency range and are also suitable for measuring bearing condition. A disadvantage is that the signal has to be integrated to measure the normalized vibration speed and that they generate little signal at low frequencies. This together makes these sensors less suitable for monitoring low-speed machines.

Vibration speed sensors have specific advantages when monitoring low-speed machines, when balancing in operating condition and when monitoring specific machines such as hammer mills and certain fans.

shaft vibrations

shaft vibrations

These vibrations are measured without contact on rotating machines with plain bearings. According to ISO 7919, two sensors (X and Y) are mounted at an angle of 90 degrees to each other. This allows the entire dynamic shaft path (lissajous) to be measured. In addition, it is possible to measure the static shaft position, both axially and radially. For vibration monitoring, the peak-peak value of the amplitude (in µm) is measured for each sensor. The maximum value of each sensor pair is decisive (max X,Y).

Usually the relative shaft vibrations are measured from the shaft to the bearing. With a relatively weak foundation it may be necessary to measure the absolute shaft vibrations. In the past this was done with a vibration speed sensor that made contact with the shaft by means of a sliding shoe. Nowadays this is also possible contactless with a special sensor.

Limits for the maximum allowable vibrations are given by the applicable parts of ISO 7919.