RTD Sensor Overview

Thermometrics Corporation manufactures a complete line of temperature detectors including resistance temperature detectors.

2-Wire RTD

Using the 2-wire method, the two wires that provide the RTD with its excitation current and the two wires across which the RTD voltage is measured are the same.

3 wire rtd

3-Wire RTD

In a three wire RTD one of the wires is connected to one side of the temperature element and the remaining two wires are connected to the other side of the element. .
4 wire rtd

4-Wire RTD

The optimum form of connection for RTDs is a four-wire circuit. It removes the error caused by mismatched resistance of the lead wires..


Pierce Probe Sensors

Piercing probe temperature sensor is manufactured with heavy wall tubing to provide support for production line handling and a spring relief.


HVAC RTD Sensors

Our HVAC assemblies are made for easy installation, high reliability, and compatibility with most building automation systems.
field_adjustable_RTD_ sensor

Field Adjustable Sensor

Field Adjustable Sensors are ideal for applications involving various sheath lengths that are best determined on site, rather than on an engineering drawing.

RTD Temperature Elements

For measuring high temperatures you should use a sensor, which reliably works in rough environments, has a long expectancy of life andideally comes up with the space-saving concepts of the automotive industry.
RTD temperature elements

Thin Film RTDs

Platinum Thin Film RTD Elements are fabricated using state-of-the-art thin film processing techniques, resulting in an element of exceptional quality and stability.

Embedment RTDs

Recognition of rising temperature can provide a warning of the breakdown of the bearing lubricating oil film; thus allowing machine shutdown and maintenance to take place. Prevention is always better than replacment.

Sanitary RTDs

Sanitary RTD sensors provide precise temperature measurements for Sanitary applications found in the Food, Dairy, Beverage, Pharmaceutical and Chemical Industries.

Averaging Sensor

The averaging RTD sensors listed below measure the temperature over the entire sheath length to provide an average temperature measurement of the cross sectional area of air ducts, room gradient temperatures, and other low temperature averaging applications.

Platinum Thermometer

Resistance thermometers,(RTDs), are temperature sensors that exploit the predictable change in electrical resistance of some materials with changing temperature.


PT100 sensors offer excellent accuracy over a wide temperature range (from -200 to +850 C).
PT1000 RTD

PT1000 RTD

The Pt1000 has 1000 ohms resistance at 0 C. These sensors are normally fitted into some type of protective sheath or mounting to form a probe.
Flex Armor Thermocouple

Flex Armor Thermocouple

Flex armor temperature sensors are commonly used in extruder and plastic processing and bearing industries.

Bayonet RTD

Bayonet RTD

Universal design allows for quick thermocouple or RTD installation into existing twist-lock adapters.
Weld Pad Sensor

Weld Pad Sensor

Weld Pad RTD and Thermocouple sensors are commonly used in Petro-Chemical industries. These sensors are welded to pipe to provide a measurement of process temperature.
RTD Resistor

RTD Resistor

A Resistor is a two-terminal electronic component that produces a voltage across its terminals that is proportional to the electric current passing through it in accordance with OHM's law.
Wire Wound Element

Wire Wound Element

Wire wound elements are basically a "hand made" product which involves lot of skilled Labor. It is manufactured by placing a coil of thin wire into a ceramic insulator. The resistance of the coil is suitably adjusted to the ohms corresponding to that particular temperature.

RTD Sensor Quotation





RTD or Thermocouple Combination

Thermometrics has combined a RTD and a type K thermocouple in one convenient assembly. This sensor is manufactued with high temperature ceramic cement and fiberglass insulated wire, to provide the maximum operating range for the thermocouple.


Why is 3-A Sanitary Temperature Measurement Important?

3-A sanitary system accepted practices pertain to the sanitation aspects of equiptment used to produce frozen desserts, egg, milk, cottage cheese, and similar food and dairy products.

RTD Temperature Sensor

Resistance Temperature Detectors: Theorys and Standards.

With these general guidelines to the basic function, performance and recognized standards for RTDs, anyone can specify the right sensor for their particular application. Setting the specifications for any sensor or instrumen t can be a difficult process, and RTDs are no exception. No one needs can be expected to be expert in all fields, and frankly, no one needs to be. With thses general RTD guidelines, along with a little common sense and background information on the application, you will successfully detail the specifications of an RTD that will satisfy your requirements.


RTD Signals: Which gives you the most accurate reading?

Wiring the RTD directly to the controller will give a slightly better accuracy if the wire length is short. But, if the best accuracy can be obtained by having the RTD and transmitter fine tuned in a calibration bath. Most of the permissible deviations can be adjusted out, and then accuracy of the RTD/Transmitter unit will be better than that of the individual components.

What is a Platinum RTD?

esistance temperature detectors (RTDs) operate on the inherent propensity of metal to exhibit a change in electrical resistance as a result of a change in temperature. We are all aware that metals are conductive materials. It is actually the inverse of a metal's conductivity, or its resistivity, that brought about the development of RTDs. Each metal has a specific and unique resistivity that can be determined experimentally. This resistance, "R", is directly proportional to a metal wire's length, "L", and inversely proportional to the cross-sectional area, "A":


where: = the constant of proportionality, or the resistivity of the material

RTD Fabrication

Platinum RTD elements take either of two forms: wire-wound or thin film. Thermometrics wire-wound elements are made primarily by winding a very fine strand of platinum wire into a coil until there is enough material to equal 100Ω of resistance. The coil is then inserted into a mandrel and powder is packed around it to prevent the sensor from shorting and to provide vibration resistance. This is a time-consuming method and all work is done manually under a microscope, but the result is a strain-free design. Strain-free elements are required for industrial measurements below -200°C. They also insure superior interchangeablity and stability to the highest temperatures.

RTD Accuracy/Interchangeability, Stability & Repeatability

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IEC standard 751 sets two tolerance classes for the interchangeability of platinum RTDs:
Class A and Class B:

Class A: Δt °C = ± ( 0.15 + 0.002 • | t | )

Class B: Δt °C = ± ( 0.30 + 0.005 • | t | )


| t | = absolute value of temperature in °C

Class A applies to temperatures from –200°C to 650°C, and only for RTDs with three or four-wire configurations. Class B covers the entire range from –200°C to 850°C.

A major advantage of platinum RTDs is that calibration at as few as two temperatures offers accuracy, preserved by high stability, much tighter than even Class A interchangeability. No other temperature sensor offers specifications for stability (see following) that will preserve laboratory accuracy embedded in calibrations over long time periods and wide temperature ranges and every configuration. Primary Standard Resistance Temperature Sensors (SPRTS) are platinum for good reason.