RULA technologies have created a specialized calibration software module, which can be used together with RL-C21 vibration control system.
The typical calibration set is shown in the picture. It includes a reference sensor mounted on the shaker, a shaker and an amplifier.
If the sensor under calibration is mounted directly on the reference sensor, such a procedure is called back-to-back calibration.
Usually, a sine wave is used to excite both sensors.
When the sine wave is being generated on the shaker, the output signals of the reference sensor and sensor under calibration are measured.
After that, sensitivity is calculated by the formula:
Sc – sensitivity of the sensor under calibration;
The procedure repeats itself on five or six frequencies distributed through the frequency range of the sensor under calibration, one frequency is the minimum, one the maximum and one the reference frequency of the accelerometer.
In spite of the fact that with RULA equipment all the excitations and calculations are carried out automatically, without any input from the user, sine excitation procedure takes long time.
Therefore, in addition to sine wave excitation, TestUp software provides calibration with Random signal excitation. In this case, the shaker is excited with a random signal, which contains all the frequencies in the sensor frequency range. If a random signal is used, sensitivities on all the frequencies are measured simultaneously. This way reduces the calibration time to three or four minutes.
Traditional back-to back calibration can be inaccurate if the sensor under calibration is bigger or heavier than the reference sensor. The error grows with the increase of frequency. To avoid such an error, in TestUp software we implemented the procedure of calibration by substitution.
Besides correcting the errors caused by the sensor mass and sizes, calibration by substitution eliminates the errors caused by the non-linearity of measurement channels and reduces the uncertainty of measurements.
Besides the automated measurements, a manual measurement mode is implemented in TestUp.
The mode allows specifying the frequency and amplitude (in acceleration, velocity or displacement units) manually and checking the response from the sensors. The mode is highly useful for research purposes.
RULA Technologies have developed an extensive subsystem of vibration transducer calibration.
It is an innovative, yet easy-to-use software, which provides automated calibration of a wide range of vibration sensors. The system uses a range of calibration methods, innovative and well-established, according to ISO 16063-21.
Our advantages are: