Traceable Accelerometer Calibration at Temperature
Many vibration tests are carried out under the influence of temperature, whereby accelerometers are attached to the vibration exciter and/or to the device under test. These are thus exposed to temperatures which can be far above or below room temperature, which is where the sensors are usually calibrated. Calibration of the sensors in the temperature range of the application is therefore essential, to correct for the influence of temperature on sensor sensitivity, which can be significant. SPEKTRA has developed a calibration method which, in addition to the temperature range from -55°C to 120°C, can also cover the wide frequency range from 10 Hz to 10 kHz. The method is based on a comparison calibration against a reference acceleration sensor according to ISO 16063-21, where the vibration exciter with reference sensor is integrated into a temperature chamber. Thus, it is possible to calibrate not only at room temperature but over the entire temperature range mentioned above. The reference sensor can be calibrated for this purpose by means of a combination of highly accurate primary calibration at room temperature and additional primary and comparative calibrations under the influence of temperature, whereby a complete traceability of the measuring chain to national standards is still ensured. In particular, consideration is also given to the difficult mechanical conditions which arise as a result of the necessary thermal barrier between the table of the vibration exciter and the reference sensor, and which thus so far have restricted the frequency range to a few kHz.