Abstract:
This article discusses the factors affecting the accuracy of temperature transmitters. First, different temperature ranges on the transmitter result in varying accuracy levels. For instance, Pt100 input temperature transmitters show different accuracies across diverse temperature ranges. Second, the wiring method matters. RTD sensors require two-, three-, or four-wire connections, and thermocouple sensors need compensating wires, all of which impact accuracy. Lastly, environmental conditions such as temperature, humidity, electromagnetic fields, vibration, and power supply also play a role. Understanding these factors is crucial to ensure temperature transmitters function effectively in industrial measurement and control systems.
Functions:
The temperature transmitter functions to receive signals from on-site temperature sensors like thermal resistors, thermocouples, and thermistors. After isolation and linearization, it converts these into standard analog or digital signals linearly related to the temperature for output.
As a crucial part of temperature monitoring, temperature transmitters find wide application in various industrial measurement and control systems. Their measurement accuracy is vital for the accuracy of temperature monitoring within the system. The design scheme, component performance, and process quality of the temperature transmitter establish its own accuracy. However, other diverse factors also influence the final measured accuracy. Now, let's analyze some common factors.
Common Factors 1
First of all, different temperature ranges of the temperature transmitter can affect its measurement accuracy. To accommodate various commonly used RTD and thermocouple sensors with different index numbers, most current temperature transmitters are designed as intelligent ones. Their internal software programs allow users to set the corresponding sensor index numbers and temperature ranges. Meanwhile, the hardware is designed with a unified specification. Under this design, the measurement accuracy varies for different temperature ranges. For example, for a Pt100 input temperature transmitter, the accuracy is 0.2% within the 0 - 100 °C range, while it is 0.5% within the 0 - 50 °C range.
Common Factors 2
Secondly, after choosing the temperature transmitter, the wiring method used on-site also impacts its measurement accuracy. For example, RTD sensors can use two-wire, three-wire, or four-wire connections to the transmitter. With a two-wire connection, the wire resistance gets calculated into the RTD's resistance value, increasing the measurement error. In contrast, three-wire and four-wire wirings eliminate wire resistance and avoid this problem.
Another example is thermocouple temperature sensors. In the field, we need to use compensating wires of the corresponding material to connect to the transmitter. This prevents errors caused by the difference between the actual cold end position's temperature and the transmitter's measured cold end temperature. Note that whether the compensation element at the cold end of the thermocouple temperature transmitter is built-in or external also affects the accuracy.
Common Factors 3
Finally, environmental factors on site also affect the measurement accuracy of the temperature transmitter. For example, temperature, humidity, electromagnetic environment, vibration, and power supply all have a certain impact on the accuracy. We should try to install and use the temperature transmitter within the environmental conditions it specifies to meet the measurement accuracy requirements.
Conclusion
In summary, temperature transmitters are vital in industrial temperature monitoring. Multiple elements determine their accuracy. The diverse temperature ranges of intelligent transmitters result in varying accuracies, as the Pt100 example shows. Wiring methods matter significantly. Incorrect wiring like using two-wire for RTDs can increase errors, while using proper compensating wires for thermocouples is crucial to avoid inaccuracies related to cold end temperatures.
Additionally, we can't overlook environmental factors such as temperature, humidity, and electromagnetic fields. To ensure precise temperature measurement, industries must meticulously consider these aspects when selecting, installing, and operating transmitters. We're pleased to help you find the most competitive quote. Contact us at ANTELTS without hesitation.