Differences in Temperature Drift: In addition to their basic accuracy, temperature measurement instruments are subject to various factors that can compromise their precision-specifically, a decline in accuracy caused by changes in the operating environment. This specific deviation is referred to as the instrument's "temperature drift." As a critical performance metric, the lower an instrument's temperature drift, the higher its measurement accuracy and the less susceptible it is to fluctuations in ambient temperature. Even if a temperature transmitter and a digital temperature display unit share identical temperature drift specifications, the digital display unit typically experiences a greater internal temperature rise during operation than the transmitter. Consequently, the impact of temperature drift on the overall accuracy of the digital display unit is far more significant than it is for the temperature transmitter.
Differences in Accuracy: The accuracy of a temperature transmitter is typically 0.1%, whereas that of a digital display unit is usually 0.5%. Evidently, the temperature transmitter offers a level of accuracy that is five times higher than that of the digital display unit.
Differences in Service Life: The service life of a 4–20 mA two-wire temperature transmitter is significantly longer than that of a digital temperature display unit. The power supply section of the digital display unit generates substantial heat, making it highly prone to premature failure.
Differences in Cost: Generally, the unit price of a temperature transmitter is higher than that of a digital temperature display unit. However, installing a digital display unit in an industrial field environment necessitates the addition of an external protective enclosure. To simultaneously meet protection requirements and ensure the display remains legible, a transparent glass window must be incorporated-a requirement that adds considerable cost. Furthermore, unlike two-wire instruments, digital display units require an independent 220V power supply; this entails running a dedicated power cable from a distant control room and installing additional safety components, such as circuit breakers. When the total cost is calculated comprehensively, the digital display unit proves to be not only *not* cheaper but, in fact, significantly more expensive overall.
Differences in Electricity Consumption Costs: The electricity consumption of a temperature transmitter is less than one-tenth that of a digital temperature display unit. It is estimated that each transmitter saves approximately 40 kWh of electricity per year compared to a digital temperature display unit.
Differences in Installation, Operation, and Maintenance: Temperature transmitters feature fewer wiring terminals than digital temperature display units, making them easier to install and maintain. Consequently, this results in reduced expenditures related to these operational aspects.
Summary: Based on the aforementioned differences, it is inappropriate to deploy digital temperature display units-which are typically designed for indoor use-in industrial field environments. Many of their technical specifications fail to meet the rigorous demands of field applications. While their initial unit price may appear "cheap," a comprehensive analysis reveals that their cost-performance ratio is actually quite poor; over time, the cumulative costs associated with electricity consumption and maintenance will prove to be substantial.