How to Check a Faulty Temperature Sensor?

RTDs and Thermocouples are the two most commonly used devices in industrial temperature measurement. Even though both devices are very precise and reliable, sometimes they get faulty due to wear and tear, misuse, or environmental conditions. Hence, prompt identification and rectification of faults is essential for efficient and safe processes.

In this guide, we will walk you through the key steps to check a faulty temperature sensor and determine whether you’re RTD (Resistance Temperature Detector) or thermocouple needs replacement or repair.

Understanding Temperature Sensors: RTDs and Thermocouples

  1. Resistance Temperature Detectors (RTDs):

RTDs measure temperature based on the principle that electrical resistance in a metal change predictably with temperature. They are widely used for their precision and stability in applications requiring high accuracy.

  1. Thermocouples:

Thermocouples work by producing a voltage based on the temperature difference between two dissimilar metal wires. They are flexible, robust, and suitable for high-temperature applications.

Both sensors are important in process control in manufacturing, chemical processing, and HVAC systems.

Signs of a Faulty Temperature Sensor

Look out for these common indications before testing a sensor:

  • Unpredictable Readings: Erratic temperature fluctuations or values that fall outside the expected range.
  • No Signal: The sensor has no output signal.
  • Slow Response Time: Dull response to temperature changes.
  • Visible Damage: Physical wear, corrosion, or frayed wiring.

Steps to Check a Faulty RTD

  1. Check for Physical Damage: Some for loose connections, corrosion, or visible damage to the sensor and its wiring. Sure, the RTD is properly connected to the measurement device or controller.
  2. Run a Continuity Test: An RTD wire continuity using a multimeter. There should be no continuity if the wiring is broken or disconnected.
  3. Resistance Measurement: Dissociate the RTD from the circuit. Miscellaneous conditions may be checked using an ohmmeter. The measured value has to match the temperature-resistance curve of the RTD.
  4. Short Circuit Checking: The RTD leads for the presence of short circuits among the various leads or between a lead and the chassis.

Steps to Check a Faulty Thermocouple

  1. Examination of Thermocouple: Look for damaged units such as broken insulation or corroded wires. Ensure that there is no fault in the connection of the thermocouple junction.
  2. Millivoltmeter Test: Measure the voltage output using a millivoltmeter. Compare it to the reference chart of the thermocouple.
  3. Continuity Test: Check using a multimeter if there is an open circuit in the thermocouple wiring.
  4. Check the Cold Junction Compensation (CJC): Faulty compensation can lead to incorrect readings. Test the CJC in your instrumentation for proper operation.

When to Replace a Sensor

If the troubleshooting steps above indicate significant wear, inaccurate readings, or irreparable damage, it’s time to replace the sensor. Always choose high-quality RTDs or thermocouples, such as those offered by Metalogic Sensors, to ensure durability and precision in your operations.

Why Choose Metalogic Sensors?

At Metalogic Sensors, we specialize in providing industry-grade temperature measurement solutions. Our RTDs and thermocouples are engineered for accuracy, reliability, and long-lasting performance in the most demanding applications.

By following these simple troubleshooting steps and investing in high-quality sensors, you can ensure the smooth operation of your processes and prevent costly downtime. For expert advice or to explore our range of RTDs (Resistance Temperature Detectors) and thermocouples, contact Metalogic Sensors today!