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VeriFast
TM
LVDT – User Manual – FDP-VFA-LVD-UM-EL-1.15-0918
Re-Calibrating the Signal Conditioner (If necessary)
When delivered to the customer, the VeriFast LVDT is fully calibrated for use with a 22 mm weld
pin stroke. If a 50 mm weld pin stroke is being used, or if, for any other reason, you suspect that
your equipment needs to be recalibrated, follow the instructions below.
Calibrating the VeriFast LVDT Signal Conditioner consists of entering Calibration Mode and
moving the weld pin to set the extended and retracted positions, which will correspond to the
minimum and maximum output voltage. The Signal Conditioner returns to Operating Mode
immediately after both positions have been set.
1.
After power-up, 3 minutes of warm up time
is recommended.
2.
Enter the Calibration Mode by pressing
and holding both buttons simultaneously
for 3 seconds minimum. The OPER LED
will begin blinking.
3.
Move the Pin to its
extended
position and
press the 'B' button. Wait for the Position
LEDs to stop blinking.
4.
Move the Pin to its
retracted
position and
press the 'A' button. The unit will exit
Calibration Mode and operate with its new
calibration. The OPER LED will be steady
ON.
Figure 5 – LVDT Sensor Display and Operating
Elements
Calibration mode can be cancelled by pressing the two buttons simultaneously for 3 seconds.
Determining Effective Resolution
In a measurement system, resolution is defined as the smallest increment of position change
which can be detected and indicated by the output.
Factors Affecting Analog Resolution
In sensors providing an analog output, practical resolution is determined primarily by:
•
The noise on the output and/or signal lines
•
The input resolution of the device to which the sensor is connected.
Noise
is the main limiting factor in most systems. Even if the resolution of the sensor is
theoretically infinite, it’s only possible to resolve signal changes that are larger than the amount
of noise on the output signal lines. Output changes smaller than the noise level are “lost” in the
noise.
Buttons
