What is an RTD?

What is an RTD?

An RTD (Resistance Temperature Detector) is a temperature sensor that exhibits an increase in resistance when subjected to an increase in temperature. RTDs are highly accurate sensor devices with low drift and excellent long term stability.

What types of RTDs are available?

There are two main types of resistance temperature detectors, thin-film and wire-wound.

Wire-Wound RTDs

Wire wound RTDs are built using a small diameter wire, typically platinum, which is wound into a coil and packaged inside a ceramic insulator. Larger extension wires are then spot welded to the platinum wire. Conversely, the small diameter wire can also be wound around the outside of a ceramic mandrill and coated with an insulating material such as glass with extension wires then being spot welded to the winding wires.

Thin Film RTD Elements

Thin film RTDs are made by depositing a thin layer of resistive material, typically platinum film, onto a ceramic substrate. A pattern is then etched onto the element, creating the electrical circuit. Platinum Thin-film RTDs (Pt-RTDs) offer a nearly linear temperature vs resistance relationship as well as very high accuracy over wide temperature ranges. The European standard DIN/IEC 60751 is considered the worldwide standard for platinum RTDs.

The three standard accuracy classes for these RTDs at 0°C are:

DIN Class A: ±0.15°C (IEC 60751 F 0.15)

DIN Class B:  ±0.30°C (IEC 60751 F 0.3)

DIN Class C: ±0.60°C (IEC 60751 F 0.6)


EI Sensor Technologies offers Platinum Thin Film RTDs. Capable of withstanding operating temperature from -200°C up to +850°C.  Higher temperature ratings are available thru special order. Our standard resistance values for our leaded and surface mount devices are 100Ω, 500Ω and 1,000Ω with a TCR of 3,850 ppm/K (other values available) and we can supply just the sensing element or provide a full solution RTD probe assembly. Offered in a wide variety of thermowell configurations and sizes, the probe assemblies are well suited for temperature measurement in many industries such as White Goods, HVAC, Energy Management, Industrial Controls and Food Handling/Processing.

Our design engineers are available at sales@ei-sensor.com to assist with the selection of an RTD element or probe assembly for your unique application.

Supplying customers across the globe!

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