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Pt100 Probes

What is a Pt100?

Pt100 is a very popular and precise resistance thermometer. Pt is for Platinum, which the resistor is made of. 100 is for its resistance of 100 Ohms at 0 °C. As with all resistance temperature detectors (RTD), the sensing elements changes its electrical resistance with changing temperature.

Characteristics of Pt100 Sensors

Pt100 probes are linear and accurate in a wide temperature range. The temperature range of Pt100 temperature sensors extends from -50 to +500 °C. Dedicated cryogenic Pt100 probes can even go down to -200 °C. Outside of this range, we recommend the use of a thermocouple. The optimum diameter of Pt100 probes is 3 mm, but we can reduce it to 1.5 mm. For smaller diameters, again, we recommend to use a thermocouple. As opposed to thermocouples, you don’t need compensated leads with a Platinum RTD.

The Pt100 probe is a versatile and precise temperature sensor. The Pt100 is an RTD temperature probe.

Pt100

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Mineral insulated temperature probe with overmoulded M12 connector. Available as Pt100 and Pt1000.

Mineral insulated Pt100 RTD probe, M12 connector

Series: TRMSTD
Measuring range: -50 to 500 °C
Sensor: Pt100 Class AA/A/B
Connection: 4 wires
Mineral insulated temperature probe with overmoulded transition. Available as Pt100 and Pt1000.

Minderal insulated Pt100 RTD, overmoulded transition

Series: TRECOSTP
Measuring range: -50 to 500 °C
Sensor: Pt100 Class AA/A/B
Connection: 2, 3 or 4 wires
Mineral insulated temperature probe with overmoulded M8 connector. Available as Pt100 and Pt1000.

Mineral insulated Pt100 RTD probe, M8 connector

Series: TRSV8
Measuring range: -50 to 500 °C
Sensor: Pt100 Class A/B
Connection: 3 wires

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Jacopo Baronio

Jacopo Baronio

A screw-in temperature probe with M12 connector and G1/8 thread

Threaded Pt100 RTD probe, M12 connector

Series: TRC
Measuring range: -50 to 120 °C
Sensor: Pt100 Class A/B
Connection: 4 wires
Black cable probe made from TPE. Overmoulded sensing element. Available as Pt100, Pt1000 and NTC.

Pt100 RTD cable probe with overmoulded sensing element, waterproof (IP68)

Series: IKE4
Measuring range: -40 to 105 °C
Sensor: Pt100 Class A/B
Connection: 4 wires
Pt100 stator stick probe for temperature measurement in electric motors and generators

Pt100 stator winding RTD for electric motors and generators

Series: A076005A
Measuring range: -10 to 150 °C
Sensor: one or two Pt100
Connection: 3 or 6 wires

Integrated transmitters

By the way, our Pt100 temperature sensors are also available with 4-20 mA and 0-10 V output signal. These outputs offer you more flexibility and are less susceptible to interference. Take a look at our RTDs with integrated transmitter now!

Also: take a look at our Modbus temperature probe!

Four different versions of Italcoppie's evo temperature transmitters on a white background
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Jacopo Baronio

Jacopo Baronio

Frequently asked questions about the Pt100 resistance thermometer

The Pt100 is at a slight disadvantage in terms of resolution and signal strength. The base resistance of the Pt1000 is 10 times higher – so the unwanted resistance from lead wires has less influence on the measurement than with a Pt100.

On the other hand, the power loss of the Pt100 is lower for the same measuring current, so it heats up less. However, the self-heating of the Pt1000 can also be counteracted by a lower measuring current.

The resistance of the connecting cable distorts the result result of the measurement: with a Pt100, this distortion is pretty significant at about 0.4 Kelvin per metre of cable length. With a Pt100, we therefore recommend a 3- or 4-wire circuit for cable lengths of more than 1m.

Alternatively, you can either use a Pt1000, or use a transmitter as close as possible to the sensor, or directly use a temperature sensor with 0-10V/4-20mA output signal.

The output signal of a Pt100 is comparatively weak and therefore sensitive to interference. Amplification or conversion of the signal to a more robust one such as 0-10V or 4-20mA is therefore often recommended, especially when using longer cables. Our integrated transmitters also compensate for the measuring error and thus improves the accuracy.

You need a digital output signal? Take a look at our Modbus temperature sensor series!

Generally speaking, Pt100 sensors are comparatively accurate. The resistance values and accuracy classes are defined in DIN EN 60751 and IEC 751. Class AA is the one with the highest accuracy, class C the one with the lowest.

However, the accuracy of an individual sensor depends not only on the accuracy class of the measuring element, but also crucially on the cable length and the cable configuration (2-, 3- or 4-wire circuit) as well as the measuring current. As you can see: the devil is in the details. Our experts are happy to help you choose the right temperature sensor – get in touch now!

Regarding the response time of a sensor, the following rule of thumb applies: If you double the diameter, you quadruple the response time. So choose the diameter wisely!

As with all temperature sensors, the immersion length should be at least 5x the diameter of the sensor to avoid thermal bridges.