PRT (Platinum Resistance Thermometer) is a widely adopted RTD for its efficacy and precision in temperature sensing. No matter whether you need to measure temperature for scientific, industrial, or environmental purposes, nothing can outshine the RTDs.
Two of the most popular RTDs in modern process industries are Pt100 and Pt1000 RTD. They provide repeatable results and are more accurate than thermocouples, thermistors, or silicon-based sensors.
But which one can match your industry specifications better: Pt100 or Pt1000?
In this post, we will cover how Pt1000 and Pt100 differ from each other and assess their strengths and weaknesses. So if you are trying to decide which RTD is best for you, read on!
What is an RTD
An RTD (Resistance Temperature Detector) is the most popular and precise electronic temperature sensor available today. RTDs contain a conductor wire with a positive temperature coefficient as the temperature sensing component.
The most used materials are:
- Platinum
- Nickel
- Copper
Among the RTDs, Pt-made RTDs are most popular because:
- Pt has excellent corrosion resistance, which means it is highly resistive to the degeneration caused by chemical, environmental or electrochemical reactions. So, PRTs can operate in even extreme environmental conditions with precision.
- It comes with excellent stability.
- PRTs feature a temperature range between -200°C to +850°C, which is greater than other RTDs and thermocouples. It makes PRTs suitable to operate precisely in higher temperatures.
- PRTs exhibit more consistent, precise, and repeatable results. It means the temperature is the same for an identical experiment environment while measured multiple times with a PRT.
Pt1000 RTD
Pt1000 is a wire-wound or thin-film Pt-based RTD. The name Pt1000 indicates:
- The RTD is composed of Platinum
- It has a nominal resistance of 1000 ohm at 0°C
- Its resistance varies as 3.85Ω with a temperature change of 1°C
Pt100
Pt100 is another Pt-composed RTD sensor. With Pt100, we understand:
- The constituent of this RTD is Pt (Platinum)
- Its resistance change is a variant of temperature variation, and for each degree Celsius temperature change from the reference (0°C), there is a change of 0.385Ω in resistance.
Though most industries use Pt100 to measure temperature between -50°C to 250°C, it comes with a broad temperature range (-200°C to +850°C).
Operating Principle of RTDs
RTD sensors operate based on a natural quality of a conductor: its resistance changes almost linearly with the change in temperature over a specific range (the temperature range may vary with the conducting material used in the RTD).
In an RTD, the sensor component is calibrated with temperature. So, you can get the measuring temperature effortlessly by finding out the resistance at that temperature when the current flow is constant.
Here, the resistance changes proportionately with temperature variation. It means, with increasing temperature, the RTD resistance also increases and vice versa.
While measuring temperature:
- The RTD is positioned in the examining system and a constant current flows through the sensor.
- As the molecules of the conducting wire start vibrating and impede the current flow, there arises a voltage drop across the RTD.
- A transmitter set across the sensor can measure the value of the voltage drop.
- Evaluating the resistance value corresponding to the voltage drop, you can find the system temperature using the unique resistance-temperature chart for each RTD.
RTD Circuit Types
Pt1000 sensors have 3-types of current wiring configuration:
- 2-wire
- 3-wire and
- 4-wire
2-wire Configuration
It is the least accurate configuration as the output does not compensate for the lead wiring resistance between the instrument and the sensor. If short lead wires can go well and accuracy is not a concern in a specific case, 2-wire circuitry is sufficient.
3-wire Configuration
It is connecting an additional wire with a 2-wire circuitry to compensate for the lead wiring resistance error. It is the most applied PRT circuitry configuration that provides a more precise output than a 2-wire system. In a 3-wire circuitry, all three conductors should be of the same material and length.
4-wire Configuration
It is excellent for processes where absolute accuracy is crucial. Two conductors are for carrying the current through the circuit. And the other two eliminate the lead errors by measuring the resistance of each conductor and neutralising the differences if they find any.
Pt1000 VS. Pt100: Which One to Choose
Based on the quality of Pt of the detectors, both Pt100 and Pt1000 RTD exhibit identical characteristics in:
- Temperature range
- Tolerance
- Temperature coefficient
You can use them alternatively if your system is compatible with these PRTs. So, how do they differ from each other?
Let’s get into the differences between these RTDs:
- The resistance value measured with Pt1000 is 10-times larger than the output of Pt100. It makes Pt1000 more suitable and accurate to use in a 2-wire type than Pt100. As Pt1000 gives a larger resistance value, and the wire length is shorter in a 2-wire arrangement, the lead error becomes less significant. As the resistance of Pt100 is 10-times less than Pt1000, a larger portion of the output may include the lead error, causing a notable deviation from the actual value. Pt100 is best for 3-wire and 4-wire circuitry arrangements.
- While Pt1000 is mostly of thin-film, Pt100 can be of both thin-film and wire-wound.
- As Pt1000 requires less electric current to measure the larger resistance, it requires less power to operate than Pt100.
- As Pt100 requires more current than Pt1000, it generates more heat and is thus more prone to self-heating errors.
- The quality to use less power makes Pt1000 suitable for battery-operated devices for extended battery life, fewer downtimes, and increasing efficiency than Pt100. On the contrary, Pt100 is best for industrial and process purposes.
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