Calibrating an LVDT
Model 493.02 Controller Service
Calibration
99
Calibrating an LVDT
An LVDT is calibrated with a dial indicator or some other displacement
measuring device. 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. Displacement
can also be calibrated to any range within the full-scale capacity of the
sensor. Also, ranges do not have to be centered on zero.
Prerequisites Be sure the items described in “Before You Begin” on page 97 are true.
An LVDT requires a digital universal conditioner (DUC) in AC mode to
process the feedback signal. 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.
What you will need You will need a dial indicator gage (or for longer displacements a
measuring device such as a long ruler, laser, or optical detector) to
calibrate an LVDT. All calibration tools should also be calibrated to an
industry standard.
Note This calibration procedure calibrates the conditioner for an actuator
displacement of ±10 cm. You will need to adjust the procedure to
accommodate your actuator displacement.
Important Notes • During calibration, Manual Offset should always be set to zero.
• Ensure that Electrical Zero Lock on the Offset/Zero submenu is
set to Lock. After completing LVDT calibration, readjustment of
electrical zero will change the point at which linearization takes
place, disturbing other calibration settings (especially delta
k).
• Procedures for “Automated Controllers” assumes the FlexTest SE
Controller is equipped with the PC-Supervision option, and that
Exclusive Control is assigned to Station Manager. For more
information about Station Manager, see the Model 793.00 System
Software manual that accompanies your system.
Calibration Types The FlexTest SE controller’s full-range conditioner allows you to
choose Gain/Delta K or Gain/Linearization calibration for LVDTs.
The other calibration types, mv/v Pos Tension and mv/v Pos Comp are
typically not used for LVDT calibration.
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