Accelerometer Specifications Explained
This guide outlines the differences between the types of Accelerometer available.
Constant current supply
2-20mA, supply voltage 15-35V DC.
This is the range of supply voltage/currents that the IEPE accelerometer will operate with, this should allow it to work with a wide variety of off the shelf data acquisition systems.
Settling time
This is the time taken for the IEPE accelerometer’s internal electronics to settle to its bias voltage and reach its operating condition.
Cross axis error
A critical parameter when recalibrating accelerometers. The cross axis error relates to the percentage of the output measured in the primary axis of vibration which is actually due to vibration applied to the accelerometer from a cross axial direction. Typically less than 5% this parameter should always be checked at recalibration. DJB’s Konic Shear design is one of the best at minimising cross axis effects due to its radial design.
Bias Voltage
Only relevant to IEPE accels, this reflects the operating DC voltage that the integral electronics amplifier circuit operates at when powered. This will vary from one manufacturer to another and higher is not necessarily better than lower, the level is simply a feature of the electronics design.
Saturation Limit
Peak measuring range of the accelerometer.
Base strain/Base bending
Is the phenomena whereby an additional strain is applied to the piezoelectric sensing element due to the bending of the base of the accelerometer caused by a bending mode in the test item. This is not part of the vibration measurement and as such is an error. This is a common fault with compressive accelerometer designs, but less so with shear and Konic shear designs. This should be less than 5%.