Verification of accelerometers and associated instrumentation using calibrators
The simplest and most widely used method in practice of accelerometers testing and testing of kits and systems containing accelerometers is based on the application of the reference source of mechanical oscillations with exactly defined parameters, i.e. calibrated vibrator. Such device is, for example, a portable calibrator designed to test the accelerometers and associated equipment. It should be noted that the mentioned method can be used both in the laboratory and in the field conditions; and it does not impose high requirements to neither any qualification nor the experience of staff.
Portable calibrator is a calibrated pocket-size shaker running on batteries. Mechanical vibrations of the vibrating table has precisely defined frequency of 159.15 Hz (1,000 rad/s) and acceleration amplitude of 10 m/s2 (RMS), corresponding to the amplitude of the speed of 10 mm/s (RMS) and the amplitude of movement of 10 microns (RMS). Deviation of portable calibrator is less than ± 2%. Portable calibrator is effective both in the laboratory and in the field conditions and allows verification of accelerometers and kits and systems containing accelerometers. Fig. 1 illustrates the accelerometer sensitivity check by using a portable calibrator, A17-U2 Spectrum analyzer and ZETLab software.
Portable calibrator is particularly effective in the following areas:
- Verification of accelerometers and their sensitivity control.
- Verification of the calibration parameters and setting of vibrometric complexes and systems.
Verification of accelerometers and their sensitivity is simple and fast. Tested accelerometer should be fixed to a calibrator vibrating table and, when the table is working, the electrical signal given off by a preamplifier, which is coupled with the accelerometer, should be measured. The spectrum analyzer is used as a measurement device.
Great advantage of the calibrator is the opportunity to test vibrometric kits and systems containing accelerometers, preamplifiers and measuring, analyzing and/or recording equipment. The calibrator facilitates the identification and verification of the general sensitivity of complete vibrometric plants and systems without the need to determine the sensitivity value and/or gain ratio, which is/are inherent in the individual elements of these plants and systems.
In addition to the specified features of accelerometers testing and testing of kits and systems containing accelerometers, the calibrator also helps to set the gain ratio of used equipment, carried out with a view to harmonize the maximum reading of the corresponding display device with a reference value of acceleration, velocity or displacement of mechanical vibrations imparted to the accelerometer.