Instrumentation Calculators

RTD Class B Tolerance Calculator

An RTD (Resistance Temperature Detector) is a commonly used sensor for temperature measurement in various industrial applications. Class B RTDs offer good accuracy and are widely used where extreme precision is not critical. This RTD Class B Tolerance Calculator helps you determine the permissible deviation in resistance for a specific temperature, ensuring that your RTD measurements are within the defined accuracy limits according to the DIN IEC 60751 standard.

  1. Select the RTD Type: Choose the configuration of the RTD (2-wire, 3-wire, or 4-wire) used in your application.
  2. Input the Temperature: Enter the temperature in degrees Celsius (°C) at which you need to calculate the tolerance.
  3. Calculate the Tolerance: The calculator will provide the Class B tolerance value based on the DIN IEC 60751 standard, giving you the acceptable range for the RTD’s resistance at the selected temperature.

The tolerance of a Class B RTD defines its accuracy at a specific temperature. This tolerance changes with temperature and is wider than that of Class A RTDs. The tolerance for a Class B RTD is calculated using the following equation:

For Class B RTDs, the tolerance is given by:

Where:

  • T is the temperature in degrees Celsius.
  • The absolute value |T| ensures that the calculation is accurate for both positive and negative temperatures.

For an RTD operating at 150°C, the Class B tolerance is calculated as:

Tolerance=±(0.30+0.005×∣150∣)°C

Tolerance=±(0.30+0.75)°C

Tolerance=±1.05°C

This means the RTD’s resistance can deviate by up to ±1.05°C from the actual temperature, and it will still meet the Class B tolerance limits.

The following table shows the Class B RTD tolerance values according to the DIN IEC 60751 standard. These values provide the permissible deviation in temperature for different operating temperatures.

Temperature (°C)Resistance (Ω)Tolerance (°C)Tolerance (Ω)
-20018.52±1.30±0.56
-10060.26±0.80±0.32
0100.00±0.30±0.12
100138.51±0.80±0.31
200175.86±1.30±0.49
300212.05±1.80±0.65
400247.09±2.30±0.88
500280.98±2.80±1.08
600313.71±3.30±1.27
650329.64±3.55±1.36

Click here for RTD Class A Tolerance Calculator

The below table highlights the key differences between Class A and Class B RTDs in terms of tolerance, accuracy, application, and cost.

FeatureClass A RTDClass B RTD
Tolerance Formula±(0.15 + 0.0020 |T|)°C±(0.30 + 0.0050 |T|)°C
AccuracyHigher accuracy, more precise temperature measurementLower accuracy, suitable for general applications
ApplicationsCritical applications requiring precise temperature controlGeneral industrial use where ultra-high precision is not necessary
Temperature RangeSuitable for a narrower, more precise temperature rangeSuitable for a wider, less critical temperature range
CostTypically more expensive due to higher precisionLess expensive and more commonly used
Use CasesLaboratory testing, precision equipmentGeneral process control, HVAC, industrial systems

Click here for RTD Temperature Coefficient Calculation

  • Ensures adequate accuracy for industrial applications where extreme precision is less critical.
  • Aids in calibration and validation of temperature measurement instruments in general-purpose applications.
  • Guarantees that your RTD measurements comply with the DIN IEC 60751 standard for Class B tolerance.

This RTD Class B Tolerance Calculator is a valuable tool for engineers and technicians who require reliable temperature measurements in non-critical environments.

Click here for RTD Tolerance Calculation

Here you can refer more Online Instrumentation Calculators Collections

Sundareswaran Iyalunaidu

With over 24 years of dedicated experience, I am a seasoned professional specializing in the commissioning, maintenance, and installation of Electrical, Instrumentation and Control systems. My expertise extends across a spectrum of industries, including Power stations, Oil and Gas, Aluminium, Utilities, Steel and Continuous process industries. Tweet me @sundareshinfohe

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