What is Temperature Transmitter?
Temperature transmitters are devices, used for transmitting information about temperature to the processing unit. Their main function is converting the signal produced by a temperature sensor into a standard instrumentation signal, thus making the temperature information more readable. This is especially important when the process that requires temperature monitoring is remote and not easily accessible.
Temperature transmitters interface a temperature sensor, for example, thermocouple or RTD, to a measurement or control device, for example, PLC, DCS, PC, loop controller, data logger, display, recorder, etc. Typically temperature transmitters convert the thermocouple or RTD signal to a 4-20 mA output signal and are the solution for many remote temperature measurement applications.
How to use a temperature transmitter?
A temperature transmitter draws current from a remote dc power supply in proportion to its sensor input. The actual signal is transmitted as a change in the power supply current.
Specifically, a thermocouple input transmitter will draw 4 mA of current from a dc power supply when measuring the lowest temperature of the process. Then, as the temperature rises, the thermocouple transmitter will draw proportionally more current, until it reaches 20 mA. This 20 mA signal corresponds to the thermocouple’s highest sensed temperature. The transmitter’s internal signal-conditioning circuitry (powered by a portion of the 4-20 mA current) determines the temperature range that the output current signal will represent.
Physically, only two copper wires are necessary to connect the temperature transmitter output signal in a series circuit with the remote power supply and the process equipment. This is made possible since the signal and the power supply line are combined (one circuit serves a dual function).
Universal and Accessible Transmitter Calibration
During temperature transmitter calibration process, the sensor is replaced by a device that produces a range of resistances. A special device is used for calibration, that can simulate RTDs and Thermocouples. Calibration devices are programmed using a special software, connected to a computer via a USB.
Process calibration ensures extreme accuracy
In applications making heavy demands on accuracy, the combined inaccuracy of sensor and transmitter may be too great. The solution is to calibrate the transmitter to match the specific sensor. As an example, the Pt100 ideal curve of the transmitter is matched to the specific sensor via a 2-point process calibration by way of the PReset software.
Quick on-line configuration via PC software
Temperature transmitters from PR electronics are quickly configured to the specific application. All our analog transmitters and HART® transmitters permit configuration via a standard PC and our user-friendly software, PReset. Parameters for input, output, sensor error detection, and process calibration can be configured via PReset within a few minutes. Some applications call for an occasional change in the transmitter set-up to configure it to the actual process. In this respect, the PR top transmitter series is unique as these transmitters all feature on-line configuration, carried out through the transmitter’s current loop. Our bus transmitters are also universal regarding configuration as they can communicate with all the most recognised bus software systems on the market:
For further information or if you have any questions please do not hesitate to contact us.