RTDs

RTDs for stable, repeatable temperature measurement

RTDs use a platinum resistance element whose resistance changes predictably with temperature, making them a strong fit when stability, repeatability, and lower measurement uncertainty matter more than maximum temperature range.

Thermometrics builds Pt100 and Pt1000 RTD assemblies with wire-wound or thin-film elements, 2-wire, 3-wire, or 4-wire terminations, and sheath, fitting, enclosure, and lead configurations selected around the installation and accuracy target.

Key Advantages

  • Platinum 100 ohm (Pt100) and platinum 1000 ohm (Pt1000) formats for stable, repeatable measurement
  • IEC 60751-oriented builds with Class A, Class B, and tighter configurations where required
  • Wire-wound and thin-film element options based on temperature range and mechanical fit
  • 316 stainless, MI, ceramic, sanitary, and thermowell-mount assembly options
  • Configurations for immersion, surface, sanitary, ambient, and replacement service
  • Calibration and documentation support for critical measurement programs
RTD product family with process probes, surface sensors, lead-wire elements, and connection-head assemblies

Common RTD formats for process insertion, head-style service, OEM packaging, surface measurement, and lead-wire element builds.

Wiring Options

  • 2-wire — simplest; best for short lead lengths
  • 3-wire — most common; compensates lead resistance
  • 4-wire — highest accuracy for long runs/metrology
2-wire, 3-wire, and 4-wire RTD wiring reference

2-Wire, 3-Wire, and 4-Wire RTD Wiring

Use 2-wire for simple short-run installations, 3-wire for most industrial control systems, and 4-wire where lead resistance must be removed for the highest accuracy.

2-Wire, 3-Wire, and 4-Wire RTD Wiring

The main difference between these wiring methods is how lead resistance is handled. Short runs and basic instrumentation can often use 2-wire RTDs, while plant-standard control loops usually move to 3-wire, and the highest-accuracy measurement programs use 4-wire configurations.

2-wire RTD circuit diagram

2-Wire RTD

Simplest connection style. Best for short lead lengths and applications where a small amount of added lead resistance is acceptable.

3-wire RTD circuit diagram

3-Wire RTD

Most common plant configuration. It helps compensate for lead resistance and fits many PLC, DCS, and transmitter input schemes.

4-wire RTD circuit diagram

4-Wire RTD

Highest-accuracy arrangement for longer runs, calibration work, and metrology-oriented measurement where lead resistance needs to be removed from the reading.

Thin-Film and Wire-Wound RTD Elements

RTD performance starts with the sensing element. Thin-film elements support compact, fast-response builds; wire-wound elements are used when stability, temperature range, or specific mechanical fit matters most.

Thin-film style RTD sensing element

Thin-Film Element

Compact RTD element style used where smaller package size, faster response, and standard industrial accuracy are the priority.

Wire-wound RTD sensing elements

Wire-Wound Elements

Common where broader temperature capability, long-term stability, or specific mechanical fit requirements matter more than miniaturization.

Cutaway illustration of RTD internal construction

Internal Construction

Cutaway view showing how the sensing element sits within the insulated probe body before the finished RTD is fitted with a head, cable, or process connection.

Element & Accuracy Options

  • Platinum 100 ohm (Pt100) and platinum 1000 ohm (Pt1000) sensing with IEC 60751-oriented curves and tolerance classes
  • Wire-wound elements for broad range and stability; thin-film where compactness and response are prioritized
  • 2-wire, 3-wire, and 4-wire terminations selected around installation length and uncertainty targets
  • Custom lead materials, sheath diameters, insertion lengths, and transition details

Application Coverage

  • Process skids, OEM machinery, validation rigs, sanitary systems, and ambient monitoring
  • Clamp-on and surface measurement for retrofit work without breaking the process
  • Thermowell-mounted and head-style RTDs for plant-standard maintainability
  • Calibration, traceability, and documentation support for critical measurement programs

Browse RTD Product Pages

Select the RTD construction by installation style: direct insertion, head-style process service, thermowell mounting, sanitary service, surface contact, compact packaging, multipoint profiling, or bare element integration.

Insertion & Process RTDs

For direct insertion, plant process service, and maintainable thermowell-based installations.

Immersion RTD Probes

Direct-insertion platinum 100 ohm (Pt100) and platinum 1000 ohm (Pt1000) probes with custom immersion lengths and fittings.

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Industrial Head RTDs

Process RTD assemblies with terminal heads, transmitter options, and replaceable inserts.

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Thermowell-Mounted RTDs

Spring-loaded RTD assemblies sized for serviceable thermowell installations.

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Sanitary & Clean Process

For hygienic systems, washdown environments, and process equipment with cleanability requirements.

Sanitary RTDs

Tri-clamp and hygienic-thread RTDs for food, beverage, pharma, and biotech service.

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Surface, Retrofit & Compact

For external contact sensing, retrofit installation, and tight-space instrumentation packages.

Surface Mount RTDs

Weld-pad, magnet, and ring-lug RTDs for surface and equipment temperature.

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Clamp-On RTDs

Non-invasive and retrofit RTD styles for piping and vessel measurement.

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Miniature & Needle RTDs

Small-OD RTD probes for instrumentation, validation, clean fixtures, and other tight-space installations.

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Profiling & Components

For temperature mapping, multi-zone studies, and component-level RTD build requirements.

Multipoint RTDs

Profiling and multi-zone RTD assemblies for coordinated temperature mapping.

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Averaging Sensors

Wound-wire RTD and multi-junction thermocouple averaging assemblies for ducts, plenums, tanks, and distributed measurement zones.

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Duplex / Dual-Element Assemblies

RTD/RTD and mixed TC/RTD assemblies for redundant precision measurement, validation channels, and split control/alarm instrumentation.

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Resistance Elements

Wire-wound and thin-film platinum 100 ohm (Pt100) and platinum 1000 ohm (Pt1000) element coverage for custom assemblies.

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Industries Where RTD Assemblies Are Common

RTD assemblies are commonly specified where repeatability, calibration traceability, and long-term stability matter across regulated process systems, utility loops, OEM equipment, and environmental monitoring.

Pharma & Biotech

Sanitary, validation, and precision RTD assemblies for documented process systems.

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HVAC & Refrigeration

Insertion, clamp-on, and averaging-oriented RTD use across ducts, coils, and utility loops.

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Food & Beverage

Hygienic process RTDs and utility-side measurement in cleanable production environments.

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Request an RTD Quote

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RTD Resistance Table PDFs, Curves, and Standards