Abstract
Standard platinum resistance thermometers (SPRTs) are widely used in precision temperature measurement due to their exceptional repeatability and linearity. However, practical challenges such as calibration drift, self-heating effects, and mechanical stress can compromise their accuracy. This article analyzes these issues and proposes actionable solutions.

Issue 1: Calibration Drift Over Time

SPRTs are subject to gradual calibration drift due to contamination, mechanical strain, or prolonged exposure to extreme temperatures. Even minor impurities in the platinum wire or insulation degradation can alter the resistance-temperature relationship.

Solution

• Implement periodic recalibration against fixed points (e.g., triple point of water, freezing point of zinc) as per ITS-90 guidelines.

• Store SPRTs in controlled environments to minimize thermal cycling.

• Use high-purity platinum sensors (e.g., ASTM-grade) to reduce contamination risks.

Issue 2: Self-Heating Effects

Electrical current passing through the SPRT generates Joule heating, causing a temperature rise in the sensing element. This self-heating error becomes significant in low-thermal-conductivity media (e.g., air).

Solution

• Optimize excitation current: Use 1 mA or lower to balance signal-to-noise ratio and self-heating.

• For ultra-precision measurements, employ pulsed current techniques to allow thermal equilibration.

Issue 3: Mechanical Stress

Vibration, bending, or improper handling can induce micro-strains in the platinum coil, altering its resistance characteristics.

Solution

• Mount SPRTs in vibration-isolated setups for industrial applications.

• Follow manufacturer guidelines for insertion depth and orientation to avoid stress.

Conclusion
Proactive calibration management, optimized electrical parameters, and mechanical safeguards are critical to maintaining SPRT performance.