Platinum resistance thermometers (PRTs, or RTDs) are the gold standard for precise temperature measurement—when used right. They outperform thermocouples in stability and accuracy, but their sensitivity to installation and environment means small mistakes lead to big errors. Here’s how to get the most from them.

Key tech to understand:

· Resistance vs. temperature: PRTs (e.g., Pt100, Pt1000) change resistance predictably with heat (Pt100 = 100Ω at 0°C, ~138.5Ω at 100°C). This linearity makes them easier to calibrate than thermocouples.

· Accuracy classes: Class A (±0.15°C at 0°C) vs. Class B (±0.3°C)—choose based on your needs (e.g., Class A for pharmaceutical tests, Class B for industrial ovens).

Best applications for PRTs:

· Low temperatures (-200°C to 200°C): They outperform thermocouples here—no cold-junction compensation needed.

· Stable environments: Labs or chambers with minimal vibration (PRT wires are fragile).

· Long-term monitoring: Their drift is <0.01°C/year (vs. 0.1°C/year for thermocouples), ideal for aging studies.

Installation mistakes to avoid:

· Self-heating: High current through the PRT generates heat, skewing readings. Use a 4-wire setup (instead of 2-wire) to reduce current.

· Poor thermal contact: If the PRT isn’t tightly coupled to the sample, it measures air temp, not the sample. Use thermal paste or clamping.

· Electrical noise: Near motors or power lines, shield the PRT cable to prevent interference.

When to pick thermocouples instead:
For temps >600°C (PRTs degrade) or high vibration (e.g., engine tests), thermocouples are tougher. But for precision, PRTs win.

Need help choosing between Pt100 and Pt1000? Pt1000 is better for long cable runs (less resistance loss), Pt100 for high-precision lab setups.