FAQ

At Harold G. Schaevitz Industries (HGSI), we’re more than just a sensor manufacturer—we’re a trusted engineering partner for industrial, aerospace, energy, and motorsports applications. From rugged environments to precision lab testing, we deliver measurement solutions you can rely on.

Here’s what sets us apart:

1. Custom Sensor Solutions for Unique Applications

Every application has its own challenges—and we specialize in solving them. HGSI offers custom-designed linear position sensors, temperature sensors, and instrumentation tailored to your specific requirements. Whether you need a modified housing, special stroke length, mounting configuration, or unique output signal—we’ve got you covered.

• Custom LVIT, LVDT, thermocouples, and RTDs
• Pressure and temperature sensors for OEM and specialty use
• Designed to meet demanding environmental or dimensional constraints

If you can’t find it off the shelf, we’ll help you design it from the ground up.

2. Expert Support from Application Engineers

Choosing the right sensor can be complex. That’s why our team of experienced application engineers is here to assist you every step of the way—from selection to implementation.

• Quick, knowledgeable technical support
• Real-world engineering experience
• Application-specific recommendations

We’re committed to providing solutions, not just products.

3. Precision Sensors Built for Industrial Demands

Our products are designed to perform in the most demanding environments. Whether it’s high heat, shock, vibration, or corrosive exposure, HGSI sensors are engineered for durability and accuracy.

• LVIT & LVDT sensors for position feedback in automation, fluid power, and energy
• Thermocouples & RTDs built for fast response and rugged reliability
• Signal conditioners & instrumentation to complete your measurement system
   

Why Choose Harold G. Schaevitz Industries?

• Custom engineering capabilities
• Technical support from real engineers
• Built-to-last sensors for harsh environments
• Proven performance across multiple industries
• Wide selection of USA-made products

From concept to installation, we help you measure with confidence.

Have a project in mind? Contact HGSI today and let’s solve your next measurement challenge—together.

When selecting a Linear Variable Differential Transformer (LVDT) for your application, one important consideration is whether to use a hermetically sealed or non-hermetically sealed model. The difference comes down to how the sensor is built—and how well it stands up to environmental challenges.

Hermetically Sealed LVDTs (Welded Body)

These LVDTs are built with stainless steel housings that are welded at the seams to form a completely airtight seal. This design prevents moisture, dust, or chemicals from entering the sensor.

Advantages:

• Superior environmental protection: Ideal for applications where high humidity, pressure, dust, or fluids are present.
• Built to last: Extended lifespan in harsh industrial or outdoor settings.

Typical Applications:

• Aerospace and aviation
• Subsea or underwater systems
• Power generation (nuclear, hydro)
• Chemical processing environments

Considerations:

• Higher upfront cost to purchase
• Preferred for mission-critical or long-term deployments

Non-Hermetically Sealed LVDTs

These sensors are typically sealed with O-rings, gaskets, or epoxy, but they’re not fully airtight. They work well in clean, dry, and controlled environments.

Advantages:

• Cost-effective: Simpler construction means lower cost
• Reliable for general use in standard industrial or lab settings

Typical Applications:

• Laboratory equipment
• Medical devices
• Factory automation in clean areas

Limitations:

• Reduced resistance to contaminants, moisture, and chemicals
• May have a shorter lifespan in harsh or fluctuating environments

Key Takeaway:

• Choose a hermetically sealed LVDT for tough environments where moisture, pressure, or chemicals are a concern.
• Go with a non-hermetically sealed LVDT for budget-friendly performance in clean, low-risk settings.

Need help selecting the right LVDT for your environment? Contact us today—our engineers are ready to help you find the best fit for your application.

It’s a common question—and a common mistake. While copper wire might seem like an easy and affordable option for extending a thermocouple, doing so can lead to inaccurate temperature readings and unreliable measurements.

Why People Think Copper Wire Is OK

Many people assume copper wire is acceptable because:

• It looks like regular wire and is familiar.
   
• There’s a belief that “wire is wire,” and all conductors behave the same.
   
• For short extensions, some think the impact will be negligible.
   
• Thermocouple theory isn’t widely understood—many people don’t realize that accurate voltage readings depend on using specific metals consistently throughout the entire cable run.
   
• In low-accuracy applications, it might even “seem” to work—until it doesn’t.

Why It’s Actually a Problem

Thermocouples rely on the Seebeck effect, which produces a voltage based on the temperature difference between two dissimilar metals. Here’s what goes wrong when you use copper wire:

1. Incorrect Materials
   Copper doesn’t match the thermoelectric properties of thermocouple wires like Chromel, Alumel, or Iron. Splicing copper in creates extra junctions that behave like unintended thermocouples.
    
2. Distorted Readings
   These new junctions generate additional voltage that interferes with the true signal, leading to false temperature readings.
    
3. Temperature Gradient Issues
   Any temperature differences along the copper extension create unintended thermoelectric effects that throw off the sensor’s output.
    
4. Calibration Errors
   Thermocouples are calibrated based on the specific thermoelectric properties of their metal types. Introducing copper into the circuit disrupts this calibration, resulting in unreliable measurements.

The Right Way to Extend Thermocouple Wires

Always use thermocouple extension wire that matches the type of thermocouple you're using (e.g., Type K, J, T, etc.). These wires are made with the same or compatible materials to preserve measurement integrity and ensure accurate signal transmission.

Need help choosing the right extension wire for your application? Contact our team for guidance!

Extending thermocouple wires seems simple—but if it’s not done correctly, you risk compromising the accuracy of your temperature measurements. Follow these best practices to ensure your readings remain precise and reliable.

 1. Use the Correct Type of Extension Wire

Always use thermocouple extension wire that matches the type of thermocouple you're using (e.g., Type K, J, T, etc.). The metals used in the extension wire must match the metals used in the thermocouple to maintain a consistent thermoelectric signal.

• Do NOT use regular copper wire. It creates unintended junctions and introduces voltage errors that will distort your readings.

2. Match Wire Polarity

Thermocouple wires are polarity-sensitive, meaning each lead has a positive and negative side made from different metals. Carefully match the correct wires when making connections—using incorrect polarity will result in incorrect temperature readings.

• Thermocouple wire insulation is usually color-coded to help identify polarity (e.g., in Type K: yellow = positive, red = negative in the U.S. standard).

 3. Keep Connections Clean and Secure

Poor or corroded connections can introduce electrical noise or resistance that affects your measurement.

• Use proper connectors or terminal blocks rated for thermocouple use.
   
• Avoid using solder at junction points—use crimped or screw terminals made from the proper metals instead to maintain a strong and stable connection.
   

 4. Minimize Junctions

Every junction is a potential source of error. Try to limit the number of splices or connections in the thermocouple circuit.
 

 5. Route Away from Electrical Noise

Thermocouple signals are low voltage and can be affected by EMI (electromagnetic interference).

• Avoid running thermocouple wires parallel to power lines, motors, or other noisy electronics.
  
   
• When possible, use shielded extension wire and ground the shield at one end.
   

Summary:

• Use matching thermocouple extension wire
   
• Observe polarity and proper connections
   
• Avoid copper and minimize junctions
   
• Shield and route wires carefully

By following these best practices, you’ll preserve the integrity of your thermocouple system and ensure reliable temperature data.

Need help selecting the right extension wire or connectors for your thermocouple system? Contact us now - our team is here to help!

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!