To establish a temperature measurement system, electronic temperature instrument needs to be wired to control system . RTD and thermocouple can be directly connected to control system I/O card or through Temperature Transmitter for signal conversion. In most application, temperature transmitter is used to convert RTD/Thermocouple signal and transmit 4-20mA signal, rather than directly wired the RTD or themocouple to I/O card
The choice of using temperature transmitter over direct wiring of RTD or thermocouple to control system provides many advantages:
- The signals generated by Resistance Temperature Detector or Thermocouple are categorized as low-level signal hence it is more susceptible to noise compared to conventional 4-20mA signal generated by transmitter.
- Reduce instrument cable type. It also means less type for cable spare.
- The junction box for temperature transmitter cables can be combined with those from other 4-20 mA transmitters.
- No need to provide special I/O card for thermocouple/RTD. Just connect the Transmitter to the Analog Input I/O card.
- Provided maintenance facilities such as diagnostic feature in smart transmitter.