What is a Pt1000 Sensor?

PT1000 sensors are part of the group of temperature sensors called Resistance Temperature Detectors or RTD’s for short. They use the principle of changing electrical resistance with changing temperature for the measurement of temperature. Other sensors that form this group which maybe more familiar include Pt100 sensors and we will provide a comparison later in this article.

As with other resistance thermometers it is important to understand the terminology used as this will assist in identifying the sensor being use, and it really is quite simple. The first part of the name Pt1000, ‘Pt’, is the chemical symbol for Platinum and this shows that the sensor is Platinum-based. The second part, 1000, indicates the nominal resistance of the sensor at 0°C. In this case 1000Ω.

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Resistance Temperature Detectors

As with all Platinum Resistance Thermometers, the measurement principle of a Pt1000 is for the resistance of the sensing element to change with rising or falling temperature. This resistance value is measured using Ohm’s law and the application of a small measuring current.

The resistance change conforms to internationally recognised standards in the same way a Pt100 sensor would. In the UK this standard is BS EN 60751:2008. This standard governs the resistance characteristics, tolerances and colour codes. Similar standards are used around the world. Pt1000 temperature probes are interchangeable from one manufacturer to another.

The most commonly used Pt1000 has a fundamental interval of 385Ω for a 100°C rise in temperature.

BS EN 60751:2008

The characteristics are set down in the relevant European and International Standards. In the UK we comply with BS EN 60751:2008 and this standard stipulates the resistance value, resistance change characteristics, tolerances and colour code for extension cables. All Pt1000 temperature sensors manufactured by Process Parameters comply with this specification and are completely interchangeable with sensors from other manufacturers.

A PT1000 temperature sensor against a white background.

Pt1000 sensor

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What are the differences between a Pt1000 and Pt100?

There are just a couple of differences between the two types of RTD sensors, the main one being the resistance value at 0°C; 100Ω for a Pt100 and 1000Ω for a Pt1000 but there are others.

As well as the base resistance for a Pt1000 being ten times that of a Pt100, so is the fundamental interval. This means that the resistance change per degree centigrade for a Pt1000 is ten times that of a Pt100.

The accuracy of a Pt1000 is however no worse than a Pt100. A Class B Pt1000 has the same temperature tolerance as a Class B Pt100.

Pt1000 Sensor Wiring

One of the main features of a Pt1000 RTD temperature sensor is the relatively high nominal resistance and fundamental interval which means that the resistance of any extension cable is generally negligible compared to the sensor. This permits the use of a simple 2 wire measuring circuit in almost all applications. Pt1000 temperature probes with a 5 metre cable would have an additional error of less than 0.1°C. For a Pt100 this would be ten times worse, perhaps 1°C depending on the cable used.

For this reason, the vast majority of Pt1000 RTD’s are supplied with a 2 wire measurement circuit as this helps to minimise the cost of the finished probe whilst also ensuring simplicity of the measuring system.

It is possible to use 3 and 4 wire connections, but this is less common and there is generally no technical reason to adopt these systems with a Pt1000.

Pt1000 Accuracy

 

How accurate are Pt1000 temperature sensors? –
The accuracy of a Pt1000 temperature probe is determined by the sensing element chosen. We are generally limited to using flat film detectors in the construction of Pt1000 temperature probes and therefore this limits the range of accuracies available.

The three tolerance bands available are:-
Class B +/-0.3°C at 0°C
Class A +/-0.15°C at 0°C
1/3 DIN +/-0.10°C at 0°C
Note that for the equivalent tolerance band, Pt1000 sensors are as accurate as Pt100’s.

Flat film sensing elements are extremely cost effective and there is not a large price differential between the different tolerance bands. Process Parameters holds stock of all three.

Pt1000 Temperature Range

 

What is the temperature range for Pt1000’s? –
As with accuracy, the temperature range of the sensor is limited by the type of sensing element used in the construction of the temperature probe. Flat film detectors are extremely versatile and can withstand the following temperatures:-

Class B -70 to +500°C

Class A -50 to +300°C

1/3 DIN 0 to +150°C

Note that in all cases the limitation is the ability of the detector to remain in tolerance rather than being an absolute temperature limit. For example, it is perfectly possible for a 1/3 DIN sensor to operate below 0°C but it may not remain in tolerance. In this case you would revert to the next tolerance band.

The construction of a temperature probe and materials used determine its suitability for a particular application. The same features apply for Pt1000 as for other temperature sensors such as Pt100, Thermocouples or Thermistors.

Construction methods & techniques

The sensing element itself is joined to an extension wire or cable in order to provide the resistance output to a point where it is measurable. Process Parameters always weld extension wires to the sensing elements as this provides a higher temperature join that soldering and gives the lowest possible resistance between the cable and detector. The sensor is then potted into the housing using various materials depending on the temperature range required and the other environmental conditions. We can provide constructions for very low temperatures down to -200°C all the way up to 500°C. In general, sensors are either terminated in a cable, a terminal housing or a connector. Process Parameters offers all these options.

Need a PT1000?

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What temperature probe designs are available as a Pt1000?

Quite simply there is no limitation in the design of probe. If it can be made as a Pt100, Thermocouple or thermistor then there is no reason why it cannot be replicated as a Pt1000.

We can manufacture Pt1000 probes in many different designs and include flying lead sensors, probes with terminal heads and we can even supply Pt1000 sensors with in-head temperature transmitters fitted if required.

More and more industrial instrumentation is now being equipped to accept a Pt1000 sensor input and this includes devices such as panel indicators, temperature controllers and data loggers.

Process Parameters can assist with your process instrumentation and temperature transmitter requirements. Contact us for assistance.

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