The IEC 60751:2008 standard, titled "Industrial platinum resistance thermometers and platinum temperature sensors", defines the technical specifications and requirements for platinum resistance temperature sensors widely used in industrial and laboratory settings. While the user references the 2008 version, the latest iteration is EN IEC 60751:2022, which updates and expands upon the earlier guidelines  Below is a summary of the key elements covered in the standard:

1. Scope and Application

• Temperature Range: The standard applies to platinum resistance thermometers (PRTs) and sensors operating within −200 °C to +850 °C, though specific devices may cover narrower ranges 

• Resistance-Temperature Relationship: PRTs follow a defined resistance-temperature function based on the International Temperature Scale of 1990 (ITS-90). The temperature coefficient (α) for platinum is specified as α = 3.851×10⁻³ °C⁻¹, calculated as:

  $$\alpha =\frac{R_{100}-R_0}{R_0\cdot 100}$$

  where $R_0$ is the resistance at 0 °C and $R_{100}$ at 100 °C

2. Key Technical Requirements

• Tolerance Classes: PRTs are categorized into tolerance classes (e.g., Class A, B) based on their accuracy. For example:

• Class A: ±(0.15 + 0.002|t|) °C

• Class B: ±(0.30 + 0.005|t|) °C
  These tolerances ensure consistency across industrial applications .

• Electrical Configuration: The standard emphasizes 4-wire (Kelvin) connections to eliminate lead resistance errors, critical for high-precision measurements

3. Stability and Calibration

• Long-Term Stability: PRTs must maintain resistance-temperature characteristics within specified limits under normal operating conditions. Factors like oxidation, mechanical stress, or contamination can degrade performance, necessitating periodic recalibration .

• Calibration Protocols: Calibration against fixed points (e.g., water triple point, zinc freezing point) is recommended to align with ITS-90. For ultra-high accuracy (<0.1 °C uncertainty), advanced interpolation equations beyond the standard’s scope may be required 

4. Environmental and Operational Considerations

• Mechanical Protection: PRTs are sensitive to vibration and shock, which can induce micro-strains in platinum wires, altering resistance values. Proper mounting and handling are critical 

• Thermal Management: Self-heating effects from excessive excitation currents (>1 mA) must be mitigated, especially in low-thermal-conductivity media like air 

5. Updates in EN IEC 60751:2022

The 2022 revision retains core principles but introduces clarifications on:

• Extended Temperature Ranges: Enhanced guidelines for PRTs operating near −200 °C or above 660 °C.

• EMI Mitigation: Recommendations for shielding and twisted-pair wiring to reduce electromagnetic interference in industrial environments