What is a Pt100 temperature transmitter?
A PT100 temperature transmitter is a device that measures temperature through changes in resistance. Its core component is platinum (Pt) metal. The resistance of this sensor changes with temperature, enabling accurate temperature measurement.
Its operation principle relies closely on the temperature coefficient of platinum metal. It’s the property of increasing resistance as temperature rises. At 0 ℃, the resistance of a PT100 sensor is 100 Ω. As the temperature changes, its resistance also increases or decreases accordingly.
To know this resistance change, a bridge circuit is typically used. This circuit consists of four resistors. One is the PT100 sensor itself. And the other three are known reference resistors.
By adjusting the reference resistors, the bridge reaches equilibrium. It results in no output voltage. Based on this, the relationship between the known reference resistors and the PT100 sensor’s resistance can be used to infer the corresponding temperature.
This temperature information is converted into a digital signal. This conversion process is accomplished using an analog-to-digital converter (ADC), which converts the analog signal into a digital signal. A microprocessor then processes these digital signals to calculate the actual temperature.
How accurate is a temperature transmitter?
The accuracy level of a temperature transmitter is typically expressed in categories or classes. Common accuracy classes include the following:
1. Standard Accuracy (Class A):
Standard-accuracy temperature transmitters offer lower accuracy, typically ±1°C or ±0.5%.
2. High-Accuracy (Class AA):
High-accuracy temperature transmitters offer higher accuracy. Typically ±0.1°C or ±0.2%, and are suitable for applications requiring higher accuracy.
3. Industrial Accuracy:
Industrial-accuracy temperature transmitters typically offer an accuracy of ±0.5°C or ±0.2%.
4. Ultra Accuracy:
Ultra-accuracy temperature transmitters typically offer an accuracy of ±0.1°C or better. And they are suitable for applications requiring very high accuracy. It’s important to note that the accuracy levels of temperature transmitters from different manufacturers and models may vary slightly.
So, when selecting and using a temperature transmitter, carefully consult the relevant product supplier and specification sheets to determine the specific accuracy level.
How to select a temperature transmitter range?
The measurement range of a temperature transmitter must be higher than the actual temperature range. Select the appropriate transmitter based on the temperature range of the measured medium.
Different suppliers have different measurement temperature ranges. Therefore, when selecting the appropriate measurement range for a temperature transmitter, it is important to agree with the supplier in advance.
