IMI Sensors: A PCB Piezotronics Div 699A07 User Manual
MAN-0192 rev A Page 28 of 39 800-959-4464
Recommended Practices
Operational Verification and Recalibration
As with all calibration systems, periodic verification of the system’s performance is
strongly recommended. This is best done by calibrating a dedicated verification
accelerometer each day that the unit will be used. This practice confirms proper
calibration of the equipment at the time of use. A precision accelerometer with a
quartz sensing element is recommended for performing operational verification.
Results of the verification should be compared to previous results obtained with that
dedicated, controlled accelerometer. If the calibration result of the verification sensor
changes, the 699A07 should be evaluated further to determine the root cause of the
discrepancy.
Field repair of the 699A07 is not possible, so if performance of the 699A07 is out of
specification, it should be sent back to IMI Sensors for evaluation, repair and
recalibration. Please contact IMI at imi@pcb.com or 716-684-0003 for a Return of
Material Authorization (RMA) number.
Standard Checks for Transducers
Linearity and frequency response checks should be performed periodically to
validate vibration transducer functionality.
Linearity is checked by submitting the sensor to different vibration levels while
frequency is kept constant (typically at 100 Hz or any other frequency specified by
the transducer’s manufacturer). The vibration is set to different levels within the
dynamic range of the sensor, trying to cover (as much as possible) from low to high
operating levels. The sensor output is recorded and checked if it remains
proportional (linear) to the sensor excitation input. Alternatively, the sensor
sensitivity can also be recorded and its deviation observed for the different test
points (it should not vary too much for sensors that are linear).
The frequency response of a vibration transducer can be tested by checking the
sensor output across different frequency points within the operational frequency
range of the transducer. Typically, the vibration level of the unit is set at a constant
value (10m/s² and 1g are common choices for accelerometers) and the sensor
output (or the sensor sensitivity) is observed and recorded at different frequency
points.
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