Low-Cost, Low Profile Temperature Transmitter

A key feature of the transmitter is the minimal-interaction span and zero calibration potentiometer action which is time saving and convenient when scaling or offsetting; an exceptionally wide range of adjustment is provided by the potentiometers to allow for easy re-calibration of the 4-20mA temperature range. For example, a type K thermocouple which has a working temperature range of 0 to 1100oC can be easily calibrated to operate between 0 to 600oC, where 4mA and 20mA represent 0 and 600oC respectively.

The 4-20mA loop powered transmitter provides an accuracy of ±0.2% of span for thermocouples type J,K & N and ±0.1% for Pt100 sensors. The output is directly proportional to the mV input signal for thermocouples and to the temperature input for Pt100 sensors.

The key benefit of using a 4-20mA interface between the sensor and the host measuring instrument is that long cable runs will not reduce the measurement accuracy. Compared with using thermocouple extension cables instead, there are significant cable cost savings since the 4-20mA loop requires only low-cost copper cable.

For multi-sensor installations, especially those using different sensor types, 4-20mA loops allow the use of standardized process indicators which can be simply configured to the appropriate temperature ranges e.g. 4-20mA corresponds to 0 to 1100oC for a type K sensor.