
Temperature is among the most monitored and tightly regulated parameters in industrial processes. Whether heating, cooling, reacting, melting, or preserving materials, temperature shapes product quality, safety, energy use, and process reliability. Even slight fluctuations can lead to defects, equipment failure, or inefficiency.
Accurate measurement is vital for stable temperature control. Sensors such as thermocouples and RTDs sense temperature fluctuations. Their raw outputs are weak voltages that often behave non-linearly and are susceptible to industrial electrical noise. Temperature transmitters are crucial; they convert these flawed sensor signals into stable, standardised outputs that PLCs, DCS, SCADA, or controllers can accurately read. This makes them the indispensable link between field measurement and process control.
A temperature transmitter is an electronic device that accepts raw input from a sensor and converts it to an electrical signal. This output can be an analogue signal, such as 4-20mA or 0-10V, or a digital communication protocol like RS-485/MODBUS.
This conversion is required as the raw signal received from the sensors can not be applied directly to appliances due to certain factors, such as:
Using a temperature transmitter solves these challenges by conditioning, linearising, and amplifying the signal. This ensures reliable and accurate measurement, significantly improving control performance and system stability.
The temperature transmitter receives input from the temperature sensor, draws current from a DC power supply, and transmits the signal by varying this current. For instance, a thermocouple input transmitter draws a current of 4 mA from the power supply when measuring the lowest temperature. Then, as the temperature increases, the transmitter draws a proportionally greater current until it reaches 20 mA, the maximum temperature the sensor can sense.
In other words, 4 mA and 20 mA correspond to the sensor's lowest and highest temperatures, respectively. For example, if the sensor's temperature range is 0-100 ℃, a 4 mA signal would correspond to 0 ℃. In the same way, 20mA would mean 100℃. When using RTD, the Wheatstone bridge is used to create a low voltage at its end. This signal is amplified to generate a 4-20mA signal.
Temperature transmitters interface directly between the control system and the temperature sensor. They isolate, amplify, linearise, and convert the sensor’s input signal, then send a standardised output to the control system. This process ensures accurate temperature monitoring and minimises interference.

Mounting Type
These transmitters are installed directly inside the sensor head – typically a DIN Form B enclosure that sits on top of the thermocouple or RTD assembly. As a result, they are positioned close to the sensing element, supporting responsive measurement.
How They Work
By converting the low-level sensor signal (mV or Ω) into a stable 4–20 mA output at the measurement point, these transmitters effectively minimise signal loss and electrical interference. This conversion capability is key to their reliable performance in industrial settings.
Use Case / Ideal Applications
Advantages
Mounting Type:
These transmitters are mounted on DIN rails, which are standardised metal rails used to mount electrical devices in control panels, junction boxes, or MCC/instrumentation cabinets.
How They Work:
Sensor leads run from the field to the control panel, where these transmitters condition and convert the signal to a stable analogue output.
Use Case / Ideal Applications:
Advantages:
Mounting Type:
Can be either head-mounted or DIN rail-mounted, but electrically they operate on a two-wire 4–20 mA loop, where the same pair of wires provides both signal transmission and power supply.
How They Work:
These transmitters regulate the loop current in proportion to the sensed temperature, eliminating the need for an additional power supply unit.
Use Case / Ideal Applications:
Advantages:
RTD (Pt-100 / Pt-1000)
RTDs (Resistance Temperature Detectors) such as Pt-100 and Pt-1000 are commonly used in industrial applications that require high accuracy and long-term stability. These sensors operate on the temperature-dependent change in the electrical resistance of platinum. They are best suited for low- to moderate-temperature ranges, offering excellent repeatability and reliability. RTDs are typically used in applications like HVAC systems, water process control, cleanrooms, pharmaceutical manufacturing, and laboratory environments, where precise temperature measurement is essential.
Key Benefits:
Thermocouples (J, K, R, S, T, etc)
Thermocouples operate based on the voltage generated between two dissimilar metals and are known for their ability to withstand very high temperatures and harsh industrial conditions. They are suitable for applications involving furnaces, heat treatment plants, foundries, boilers, and metal processing, where temperature levels can exceed 1000°C. Thermocouples are rugged, reliable, and respond quickly to temperature changes, making them ideal for dynamic and high-heat applications.
Key Benefits:
Libratherm provides a comprehensive range of loop-powered and DIN rail-mounted temperature transmitters for industrial environments. We engineer our transmitters for high accuracy, galvanic isolation, and long-term reliability in the field. Each model supports both RTD and thermocouple inputs, with options for 4–20 mA, 0–10 V, and RS-485 Modbus communication protocols.
We also offer:
Temperature transmitters provide accurate, stable, and reliable measurements in industrial processes. They convert weak sensor signals into standardised outputs. This enables precise monitoring and control in furnaces, reactors, water treatment, and HVAC systems. They maintain signal integrity, simplify wiring, and integrate with PLCs or SCADA systems. This makes them essential for automated operations. Select the appropriate transmitter type to enhance plant efficiency and measurement accuracy.