Analysis of an Intelligent Temperature Transmitter for Process Control

In recent times, transmitters that incorporate microprocessor to perform various intelligent functions have been developed by various manufacturers. This paper presents an overview of the evolution in transmitter technology while highlighting key factors which have influenced the evolution. It also identifies low power microprocessor and analog to digital converters working with the basic sensor circuit as the key propellants in the advancement of transmitter technology. Despite several sensors available in the process control industry, the authors focus on temperature sensors and analyze a typical Rosemount Intelligent Temperature Transmitter (RITT) with a view to identifying and comparing how experimental results vary from established parameters in the datasheet. Simulation results show that the resistance of the RITT’s Resistance Temperature Detector (RTD) varies directly with applied temperature. Percentage error shows acceptable points at -0.04%, 0.04% and -0.1%. For higher percentage error readings, it is necessary to connect a resistor of value between 250Ω and 1100Ω between the current loop and the transmitter. The future of transmitter technology is however the wireless sensor node (WSN) incorporating the Sensirion SHT11 temperature sensor.http://dx.doi.org/10.4314/njt.v34i3.2