MTS Series 793 - Manual (Page 130)

MTS Series 793 Tuning and Calibration
Displacement Sensor Calibration
Calibration Procedures 130
Displacement Sensor Calibration
A displacement sensor (also called an LVDT) is calibrated with a dial indicator or
some other displacement measuring device. The indicator is mounted between
the actuator rod and a stationary point.
A typical LVDT has a positive and a negative output. This is usually considered
tension and compression.
Displacement is usually calibrated such that the maximum extension and
retraction represent ±100% of the full-scale capacity of the LVDT, with mid-
displacement set at zero.
Prerequisites
Be sure the items described in “Pre-Calibration Considerations” on page 123 are
true.
An LVDT requires AC excitation, which requires either a dedicated AC
conditioner or a digital universal conditioner (DUC) configured in the AC mode.
You must know which conditioner is connected to the LVDT.
Note If you are recalibrating a sensor, use the existing calibration values as a
starting point.
Initial calibration If you are calibrating a sensor for the first time, you may find it necessary to:
• Perform an initial tuning of the sensor channel before calibration.
• Perform the procedure twice.
Recalibration
If you are recalibrating a sensor, use the existing calibration values as a starting
point.
Considerations for full-
range conditioners
Full-range conditioners allow you to choose Gain/Delta K or Gain/Linearization
for calibrating LVDTs. The mV/V Pos Tension and mV/V Pos Comp calibration
types are typically not used for controllers equipped with full-range conditioners.