FAQ

An AC LVDT (Linear Variable Differential Transformer) is designed to provide accurate and reliable displacement measurements within a defined travel range. Operating the sensor beyond this specified range can lead to performance issues and compromised data accuracy.

What Happens If You Exceed the LVDT’s Travel Range?
Exceeding the specified linear range of an AC LVDT results in loss of linearity, meaning the output signal no longer accurately reflects the actual movement. As you move further beyond the range, this non-linearity becomes more pronounced and can ultimately cause saturation of the output signal. This leads to inaccurate, unstable, or misleading measurements.

How to Avoid Measurement Issues
To ensure reliable operation:

• Select an LVDT with a travel range that meets or exceeds your application’s maximum displacement.
   
• Incorporate limit detection features in your system to alert users if the sensor travels beyond its intended range.

Choosing the right sensor and planning for maximum motion will help maintain consistent performance and extend the life of your measurement system.

Need help selecting the right LVDT for your application? Contact us today!

Minimizing electrical interference in a measurement system is essential for ensuring accurate and stable sensor readings. Here are key strategies to reduce noise and interference:

1. Use Shielded Cables

• Choose cables with shielding (braided or foil) to prevent external electromagnetic interference (EMI).
   
• Properly ground the shielding at a single point to avoid ground loops.

2. Proper Grounding

• Ensure all equipment is grounded to the same reference point to avoid ground loops.
   
• Use single point grounding configurations instead of daisy-chaining grounds.

3. Keep Signal Wires Away from Noise Sources

• Route sensor cables away from power lines, motors, transformers, and other high-current equipment.
   
• Avoid running signal wires parallel to AC power cables; if necessary, cross them at a 90-degree angle to minimize coupling.

4. Use Twisted Pair Wiring

• Twisting signal wires together helps cancel out differential noise, improving signal integrity.

5. Implement Low-Pass Filtering

• Add filters to remove high-frequency noise from the signal.
   
• Analog or digital low-pass filters can be applied depending on the system.

6. Isolate Power and Signal Grounds

• Use separate power and signal grounds to prevent electrical noise from affecting measurement accuracy.
   

7. Reduce EMI from External Sources

• Use ferrite beads or chokes on cables to suppress high-frequency interference.
   
• Shield enclosures and use metal cases for electronics to block radiated EMI.

8. Stabilize the Power Supply

• Use clean, regulated power sources to prevent voltage fluctuations from introducing noise.
   
• Consider using isolated power supplies or voltage regulators.

9. Use Optical or Galvanic Isolation

• Optical isolators and isolation transformers help prevent noise from being transferred between circuits.
   

By following these techniques, you can significantly reduce electrical interference and improve the accuracy of your measurement system. Need help optimizing your setup? Contact us today!

If you suspect an LVDT (Linear Variable Differential Transformer) is giving inaccurate readings, follow these steps to diagnose and resolve the issue:

1. Check the Power Supply

Ensure the LVDT is receiving the correct excitation voltage and frequency as specified by the manufacturer. Incorrect power input can cause erratic readings.

2. Inspect the Wiring and Connections

Loose, damaged, or improperly connected wires can lead to signal noise or incorrect outputs. Verify that all connections are secure and match the wiring diagram.

3. Examine the Signal Conditioning Electronics

If the LVDT is connected to a signal conditioner or data acquisition system, check that the settings (such as gain, offset, and filtering) are correctly configured.

4. Verify the Core Alignment and Movement

The core must move freely along the LVDT’s axis without tilting or binding. Misalignment can introduce measurement errors or non-linearity.

5. Look for Environmental Interference

Electromagnetic interference (EMI), extreme temperatures, or vibrations can impact LVDT performance. Shielding cables, proper grounding, and environmental protection can help mitigate these effects.

6. Compare Readings with a Known Reference

If possible, test the LVDT against a calibrated reference measurement tool to determine if the readings are within an acceptable range.

7. Check for Physical Damage or Wear

Over time, mechanical wear or external damage to the LVDT can affect performance. If the sensor is old or damaged, replacement may be necessary.

8. Perform a Calibration Check

If the LVDT’s accuracy is out of specification, recalibrating the signal conditioning electronics may help restore accuracy. However, if the sensor itself is faulty, recalibration may not be sufficient.

If you've gone through these steps and the issue persists, replacing the LVDT may be the best solution. Need help troubleshooting your LVDT? Contact us today!

Thermocouple degradation refers to the gradual loss of accuracy and reliability in a thermocouple due to environmental and operational factors. Over time, exposure to high temperatures, oxidation, contamination, mechanical stress, or thermal cycling can alter the properties of the thermocouple wires, affecting the voltage-temperature relationship and leading to inaccurate readings.

Common Causes of Thermocouple Degradation:

• Oxidation & Contamination: Exposure to oxygen, chemicals, or moisture can cause corrosion or contamination of the thermocouple wires, altering their electrical properties.
   
• Thermal Cycling & Aging: Repeated heating and cooling cycles can change the microstructure of the thermocouple materials, leading to drift in temperature readings.
   
• Mechanical Stress: Bending, stretching, or vibration can physically damage the wires, causing breaks or inconsistencies in the thermoelectric signal.
   
• Electrical Interference: Nearby electromagnetic fields or ground loops can introduce noise, distorting the thermocouple’s signal.

Effects of Thermocouple Degradation:

• Reduced accuracy and repeatability
   
• Increased signal drift over time
   
• Potential failure leading to unreliable or no readings

Preventing Thermocouple Degradation:

• Use protective sheathing or insulation to reduce exposure to contaminants
   
• Select thermocouples rated for the operating temperature and environment
   
• Perform regular accuracy checks and replace degraded thermocouples as needed
  
   

Thermocouple drift refers to the gradual change in a thermocouple’s output signal over time, leading to inaccurate temperature readings. This occurs when the voltage-temperature relationship of the thermocouple shifts due to changes in the physical or chemical properties of the thermocouple wires.

Causes of Thermocouple Drift:

1. Oxidation & Contamination
    
   • Exposure to oxygen at high temperatures causes oxidation, altering the thermocouple material and changing its voltage output.
      
   • Contaminants such as moisture, chemicals, or metal vapors can diffuse into the thermocouple wires, affecting their composition.
      
2. Thermal Cycling & Aging
    
   • Repeated heating and cooling can cause microstructural changes in the metal, leading to gradual shifts in the thermoelectric properties.
      
   • Prolonged exposure to extreme temperatures can cause grain growth, reducing stability.
      
3. Diffusion Effects
    
   • At high temperatures, atoms from the thermocouple conductors can diffuse into each other or react with their surrounding insulation, leading to composition changes and altered output.
      
4. Mechanical Stress & Handling
    
   • Bending, twisting, or vibrations can strain the wires, introducing inconsistencies in the thermoelectric signal.
      
5. Electrical Interference
    
   • Ground loops or electromagnetic interference from nearby equipment can introduce noise into the signal, mimicking drift.

Effects of Thermocouple Drift:

• Gradual loss of accuracy
   
• Increased deviation from actual temperature
   
• Unreliable measurements, affecting process control and product quality

How to Minimize Thermocouple Drift:

• Use thermocouples rated for the specific temperature and environment
   
• Protect thermocouple conductors with appropriate sheathing and insulation
   
• Perform regular accuracy checks and calibrations

Replace thermocouples when significant drift is detected
 

Thermocouples themselves are not typically calibrated in the traditional sense. Instead, calibration is primarily performed on the electronics that interpret the thermocouple’s voltage signal.

How Thermocouple Calibration Works

• A thermocouple generates a voltage based on temperature, which is then interpreted by a measuring device, such as a signal amplifier, digital readout or data acquisition system.
   
• Calibration ensures that the electronics accurately interpret the thermocouple’s output voltage at known temperature points.
   
• Adjustments are made to the instrumentation, not the thermocouple itself.

What If My Thermocouple Is Inaccurate?

• If a thermocouple is suspected of providing incorrect readings, the first step is to verify the measurement setup, including connections and wiring.
   
• If inconsistencies persist, the measuring equipment can often be recalibrated to correct any interpretation errors.
   
• However, if the thermocouple itself has drifted or degraded over time, it may need to be replaced rather than adjusted.

Do You Need a Replacement?

If your thermocouple is consistently inaccurate and calibration adjustments do not resolve the issue, contact us for assistance in selecting a suitable replacement!

If you suspect your thermocouple is providing incorrect temperature measurements, there are several steps you can take to diagnose and resolve the issue.

1. Verify the Measurement Setup

Before assuming the thermocouple is faulty, check the following:

• Ensure proper connection to the instrumentation (loose or corroded connections can affect readings).
   
• Confirm that the correct thermocouple type (e.g., Type K, J, T, etc.) is selected in the measuring device.
   
• Inspect the wiring for damage, wear, or reversed polarity.

2. Compare Readings Against a Known Reference

• Use a secondary temperature sensor (such as a calibrated RTD or another thermocouple) to cross-check readings.
   
• If possible, place the thermocouple in a controlled temperature source (e.g., an ice bath at 0°C or a dry block calibrator) to verify accuracy.

3. Consider Calibration of the Measurement System

• Thermocouples themselves are not typically adjusted during calibration. Instead, the electronics that interpret their signal (such as digital displays or data acquisition systems) are calibrated to ensure accurate readings.
   
• Calibration involves verifying that the system correctly interprets the thermocouple’s voltage output at known temperature points.
   
• If discrepancies are found, adjustments can often be made to the electronics to correct for any measurement errors.

4. Replace the Thermocouple if Necessary

If the thermocouple consistently provides inaccurate readings and calibration adjustments to the electronics do not resolve the issue, the thermocouple itself may have degraded or drifted beyond acceptable limits. In this case, replacing it is often the best solution.

Would you like assistance in troubleshooting or selecting a replacement thermocouple? Contact us today!

An LVDT (Linear Variable Differential Transformer) core extension rod is a critical component that allows the sensor’s core to move freely while maintaining precise position measurement. It serves as a mechanical link between the LVDT core and the moving target, enabling accurate signal output even in applications where direct coupling to the core is not possible.

How Does a Core Extension Rod Help?

1. Extends the Reach of the LVDT Core and Enables Remote or Hard-to-Reach Measurements
   In many applications, the measured target is positioned away from the LVDT sensor. The extension rod bridges this gap, enabling the core to move with the target without repositioning the sensor. It also allows the sensor to be mounted in a protected location, shielding it from harsh environmental conditions while still accurately tracking movement at the measurement point.
    
2. Supports Customization for Various Applications
   Extension rods can be customized in length, diameter, and material to fit specific application needs. Whether for industrial automation, aerospace, or heavy machinery, the right extension rod can help to ensure optimal sensor performance.

Choosing the Right Core Extension Rod

Material Matters – The mechanical connection to the core should be made using a non-magnetic material, preferably 300-series stainless steel, fiberglass, or a plastic rod, secured with a suitable adhesive or thread locker. Highly conductive materials such as aluminum or brass should be avoided, as they may generate eddy currents within the LVDT, leading to unacceptable measurement errors.

Proper Length and Diameter – The rod must be sized appropriately to maintain smooth operation and stability.

Would you like recommendations on LVDT core extension rods for your application? Contact us today!

Both AC and DC LVDTs (Linear Variable Differential Transformers) are used for precise linear position sensing, but they differ in operation, signal processing, and application requirements. Here’s a breakdown of the key differences:

1. Excitation & Signal Processing

• AC LVDT: Requires an external AC excitation source (typically 1-10 kHz) and signal conditioning to convert the output into a usable DC voltage or current.
   
• DC LVDT: Contains built-in electronics that provide a DC excitation and output a conditioned analog signal (typically ±10VDC, 0-10VDC or 4-20mA).

2. External Signal Conditioning

• AC LVDT: Needs an external signal conditioner or amplifier to process the raw AC signal.
   
• DC LVDT: Has integrated signal processing, eliminating the need for an external conditioner.

3. Electrical Noise & EMI Susceptibility

• AC LVDT: Less susceptible to electrical noise and ground loops, making it ideal for harsh environments.
   
• DC LVDT: More susceptible to noise due to built-in electronics, requiring proper shielding and grounding. 

4. Operating Temperature & Environmental Conditions

• AC LVDT: Handles higher temperatures and more extreme conditions because there are no built-in electronics that could be damaged.
   
• DC LVDT: Limited by the operating temperature range of its internal electronics.

5. Application Suitability

• AC LVDT: Best for high-temperature, rugged, or hazardous environments where signal conditioning can be placed remotely.
   
• DC LVDT: Ideal for simpler applications where ease of installation and a direct signal output are preferred.

Which One Should You Use?

Choose an AC LVDT when environmental conditions are extreme, long cable runs are needed, or high precision with external signal conditioning is required.

Choose a DC LVDT when you need a self-contained solution that’s easy to install with a direct voltage or current output.

Special Limits of Error (SLE) and Class 1 accuracy are similar in that they both refer to higher accuracy thermocouples, but they are not exactly the same because they are defined by different standards with slightly different tolerances.

For many thermocouple types (e.g., Type K), Class 1 and SLE tolerances are very close, but they may not always be identical. If exact compliance with a specific standard is needed, it’s best to compare the tolerances in the respective standards for the given thermocouple type.

Key Differences

1. Special Limits of Error (SLE) has a tighter tolerance than Class 1 at most temperatures.

2. SLE uses a factor of 0.002×T, while Class 1 uses 0.004×T, meaning SLE allows half the percentage error in some cases.

3. Class 1 covers a lower temperature range (-40°C and up), whereas SLE starts at 0°C.

Summary

• SLE is more precise than Class 1 at many temperatures.

• Class 1 allows a slightly larger error margin compared to SLE in most cases.

• If your application requires the highest accuracy, SLE (ASTM E230) is the better option.

• If your application requires compliance with IEC standards, Class 1 is the correct classification.