Temperature Measurement · Glossary

What is RTD Self Heating?

error from measuring currentTemperature Measurement

RTD self heating is the rise in sensor temperature caused by the measuring current flowing through the element.

RTD Self Heating Explained

The measuring current dissipates I²R in the element, warming it above the process. The error depends on current and on how well the sensor loses heat: worse in still air, small in flowing liquid.

Transmitters use small currents, typically below 1 mA, to keep the error small.

RTD Self Heating Formula

ΔT = I² × R ÷ E

I	measuring current (A)
R	element resistance (Ω)
E	dissipation constant (W/°C)

Example: 1 mA in 100 Ω gives 0.1 mW; with E = 2 mW/°C, ΔT = 0.05 °C.

Calculators for RTD Self Heating

CalculatorRTD Self Heating CalculatorFree online calculator with formula and worked example.CalculatorRTD CalculatorFree online calculator with formula and worked example.

Frequently Asked Questions

What is RTD Self Heating?

RTD self heating is the rise in sensor temperature caused by the measuring current flowing through the element.

How is self heating tested?

IEC 60751 describes measuring at two currents and comparing; the difference shows the effect.

Does Pt1000 self heat more?

At the same current, yes, ten times the power. Pt1000 inputs therefore use smaller currents.

Learn more on the blog

What is an RTD and how it works

A practical guide on instrumentationblog.in with more detail on RTD self heating and how it is applied on real plants.

Read Full Article

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