How to Calibrate Your LVDTs for Accurate Measurements

• May 29, 2025

How to Calibrate Your LVDTs for Accurate Measurements

Linear Variable Differential Transformers (LVDTs) are among the most precise and reliable sensors used to measure linear displacement. However, like any precision instrument, achieving optimal performance from an LVDT depends heavily on proper calibration. Whether you’re working in aerospace, industrial automation, or materials testing, accurate calibration ensures that your LVDT readings are trustworthy and repeatable. Learn more about how LVDT works, its common applications and how to choose a LVDT for your setup.

LVDT calibration is the process of adjusting the sensor’s output to correspond accurately with known displacement values. This involves setting up the sensor to read zero at a reference position (null point) and scaling the output so that it matches the true displacement across the sensor’s full measuring range.

Calibration helps eliminate errors caused by:

• Sensor mounting tolerances
• Environmental changes (temperature, vibration)
• Electrical drift or signal interference
• Mechanical wear or changes in the core movement

Why Do We Need to Calibrate Our Sensor

Even though LVDTs are inherently precise due to their contactless and frictionless operation, external factors can influence measurement accuracy. Calibration ensures:

• Consistent and repeatable measurements
• Accurate alignment with real-world displacement
• Compliance with industry standards (ISO, ASTM, etc.)
• Reliable performance in control or monitoring systems

What Tools and Equipment Do You Need to Calibrate LVDT?

To perform an effective LVDT calibration, you’ll need the following tools:

• Reference displacement system (e.g., micrometer stage, digital caliper, or linear actuator)
• Stable signal conditioner or LVDT amplifier with known input/output behavior
• High-resolution data acquisition system (DAQ)
• Mounting fixtures to eliminate mechanical misalignment
• Environmental controls (if calibrating in variable conditions like temperature)

Step-by-Step LVDT Calibration Procedure

1. Set Up the Mechanical Alignment

• Mount the LVDT securely and align it with the displacement axis.
• Ensure the core moves freely without touching the bore or binding.

2. Connect Electronics

• Wire the LVDT to its signal conditioner or amplifier according to the manufacturer’s instructions.
• Power on the system and allow it to warm up for a few minutes for stable readings.

3. Define the Zero or Null Position

• Move the LVDT core to its mechanical centre (or the intended zero point).
• Adjust the zero-offset using the signal conditioner so the output reads 0 V (or the baseline output defined by your system).

4. Perform Span Calibration

• Move the core to a known displacement point using your reference stage.
• Record the sensor’s output voltage.
• Repeat the process for several points across the full travel range.
• Use these data points to create a calibration curve (voltage vs. displacement).

5. Adjust for Linearity and Gain

• Adjust gain settings on the signal conditioner to ensure linear output across the range.
• Compare your actual readings with the expected linear trendline to identify any deviations.

6. Validate the Calibration

• Run a second round of measurements and compare them to your calibrated curve.
• Confirm repeatability by moving the core back and forth multiple times.
• If needed, apply software corrections to fine-tune output accuracy.

Best Practices for Reliable Calibration

• Calibrate in Stable Environmental Conditions: Temperature changes can affect materials and electronics.
• Use Precision Equipment: The accuracy of your reference measurement system determines the effectiveness of calibration.
• Document the Process: Keep records of calibration points, equipment used, and environmental conditions.
• Repeat Calibration Regularly: Especially in mission-critical or high-precision applications.
• Minimize Vibration and Electromagnetic Interference (EMI): These can skew results and affect signal stability.

Common Calibration Errors to Avoid

• Misalignment between core and coil
• Ignoring warm-up time before calibration
• Using worn or imprecise reference measurement tools
• Calibrating in uncontrolled environments (e.g., drafty, hot, or humid)
• Assuming factory calibration is still valid after sensor installation

Proper calibration of LVDT sensors is essential to maintain their high level of accuracy and performance. You might be curious how frequently sensors need calibration in general, but the answer is there is no specific time frame for each sensor. It depends on the specific application and usage. However, as a general guideline, annual calibration is recommended to maintain accuracy. By following best practices, using the right tools, and regularly validating your setup, you can ensure reliable displacement measurements in any application.

Need Help with LVDT Calibration or Selection?

At MeasureX, we provide not only high-performance LVDT sensors, but also customised systems and calibration support tailored to your application. Contact MeasureX today to speak with a specialist or visit our website for more information on calibration and accuracy.