Measuring vibrations at high temperatures
21/12/2020
Kistler has launched the 8248A3 triaxial accelerometer, a sensor that it claims can withstand high temperatures of up to 260°C.Due to a new patented technology, the sensor stands out for its stability, particularly when exposed to severe temperature changes. It is significantly smaller and lighter than other piezoelectric sensors for vibration detection, making it suitable for many applications where limited space, the weight of the sensor or an increased and varying ambient temperature play a role.
Whether in trains or in cars, demands regarding passenger comfort are on the rise. Engineers work to avoid undesirable noises caused by vibrating components inside and outside the vehicle. This requires precise measuring methods. The sensors must be able to cope with high ambient temperatures, particularly when measuring vibrations of the powertrain or the exhaust system of a vehicle. The same applies to railway engineering or vibration monitoring in power plants. The new 8248A3 miniature accelerometer provides reliable results on vibrations in all three dimensions at temperatures of up to 260°C. Two different ceramic materials are used in the sensor itself, which react differently to temperature changes and balance each other out. This makes the sensor significantly less sensitive to temperature fluctuations.The mass of the accelerometer influences the natural frequency of the measured object, which has a negative effect on the results. To prevent this effect, the new sensor is significantly smaller and lighter than comparable sensors. The smaller size of the sensor is also an advantage where space for measurement technology is limited.
The natural frequency of the sensor itself is a decisive factor in the measurement of vibrations: if a force acts on the object to be measured, not only does the object start to vibrate but also the sensor. Piezoelectric sensors, such as the 8248A3 accelerometer, have a high natural frequency due to the stiffness of the crystal component. This high frequency minimises the influence of the sensor’s own vibrations on the measuring results, which enables very demanding applications, such as precise measurement of z-forces in knock monitoring for engine development. The wide measuring range of ±2000 G with high linearity makes the new temperature-stable sensor with charge output suitable for a variety of applications.
