Choosing the right temperature sensor is no easy task. With so many different options available, knowing which one is right for your application can seem like an overwhelming decision. For example, should you be opting for a resistance temperature detector (RTD) or a negative temperature coefficient (NTC) thermistor?
And even within each of those categories there are choices to be made. Among RTDs, for instance, there is the pt100 and the pt1000, supplied by the likes of RS Components. But what exactly are they and what are their main differences? Read on to find out more.
What are pt100 and pt1000 sensors for?
They are used to measure the temperature of air, surfaces or liquids in conjunction with thermometers and other data recording equipment. They’re commonly found in a range of applications such as air conditioning units, ovens and grills, laboratories as well as food processing equipment.
Where does the name come from?
The letters “pt” represent the chemical symbol for platinum, which is what the sensor is made from. The numbers 100 and 1000 refer to the ohmic value of the sensor at zero degrees centigrade. These types of RTDs have different tolerances, each of which is defined by the IEC 60751:2008 standard.
What’s the difference between RTD and NTC sensors?
- NTC thermistors can only measure up to 130°C, whereas some RTDs can measure 500-600°C.
- In RTDs, resistance increases as the temperature increases. In NTC thermistors, the resistance decreases as the temperature increases.
- The resistance in an RTD is linear whereas in an NTC thermistor it is exponential.
- Typically, NTC thermistors are less expensive than RTDs.
- An NTC thermistor usually picks up fluctuations in temperature much faster, which leads to quicker response times.
What are the benefits of using a pt100 or pt1000?
- Great consistency
- High accuracy
- Long-term stability
- Can endure high temperatures
What are the differences between pt100 and pt1000?
- The pt100’s ohmic value at 0°C is 100Ω, whereas for the pt1000 it is 1000Ω.
- The pt100 is more suited to three and four-wire circuit configurations, because resistance is lower so any external resistance will have a greater impact on the ability to make an accurate reading. The pt1000 is more suited to two-wire circuit configurations.
- Pt100s tend to be more common because they are compatible with a wider range of applications.
- A pt1000 sensor is more suited to applications that run on battery power, while their reduced self-heating when compared to pt100 means fewer inaccuracies in readings.
- Pt1000s are usually only available with thin-film element constructions. A pt100, on the other hand, can be found with either thin-film or a wire-wound element construction.