Now it is simple and cost-effective to retrofit 4-20mA temperature transmitters to existing Pt100 or thermocouple sensors without removing them from the process or having to replace them with alternative assemblies.
The Labfacility ILTX in-line transmitter, which the company claims to be unique, is a small plug-in module that simply connects to an existing or new insulated sensor without the need for a special assembly or connecting head. In many industrial and scientific applications where heavy-duty housings are not required, the rugged ILTX provides a quick, convenient means of establishing a two-wire transmission loop. It is suitable for light industrial use, laboratories, instrumentation departments, educational establishments, research facilities and research and development environments.
Each ILTX can be used as a free-mounted unit or surface-mounted via integral fixing lugs. Connections are made using miniature connectors that are polarised to prevent cross-connection, and colour-coded to suit the sensor type.
A key feature of the transmitter is the minimal-interaction span and zero calibration potentiometer action that saves time and is 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 with a working temperature range of 0-1100degC can be easily calibrated to operate between 0-600degC, where 4mA and 20mA represent 0 and 600degC, respectively.
Compact and lightweight, the potted module houses an accurate, stable measurement circuit that incorporates automatic cold junction compensation for thermocouple inputs. Since the ILTX is designed to be connected to the extension cable that exits the temperature probe, particular attention has been paid to eliminating the effects of possible noise pick-up at the input.
The 4-20mA loop powered transmitter provides an accuracy of +/-0.2 per cent of span for thermocouples type J,K and N and +/-0.1 per cent for Pt100 sensors. The output is directly proportional to the mV input signal for thermocouples and to the temperature input for Pt100 sensors.
A key benefit of using a 4-20mA interface between the sensor and the host measuring instrument is that long cable runs do not reduce the measurement accuracy. Compared with using thermocouple extension cables, 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 standardised process indicators that can be simply configured to the appropriate temperature ranges. For example, 4-20mA corresponds to 0-1100degC for a type K sensor.
The ILTX is CE and RoHS compliant and is guaranteed for two years.
