A typical temperature sensor installation uses a thermowell or other prove to reach in the process where it can sense the required temperature. Having a transmitter at the device minimizes the reduces the likelihood of signal contamination from electromagnetic interference. Source: Moore Industries
　　Almost ten years ago, I was saddled with the task of overseeing startup of a pollution control system our company had provided for a lime producer. It involved measuring the temperature of fl

ue gas which seemed simple enough. HoweverCONTROL ENGINEERING China版权所有, between my group, our system integrator, our parent company, the local operatorsCONTROL ENGINEERING China版权所有, the customer’s engineering contractor, and the customer’s parent company, we had many differences of opinion as to what type of sensor was best. The discussions created almost as much heat as the kiln. Before the commissioning was over, we installed two types of Thermocouples and at least one RTD (resistance temperature device), including pulling appropriate cables for each. It was an expensive lesson.
　　Choosing can be difficult, even though there are only three main technologies for measuring temperature electronically:
　　Thermocouple;
　　RTD; and
　　Thermistor.
　　ONLINE extra Also read a tutorial: Understanding the tricky thermocouple, with diagrams.
　　It is easy to make generalizations about the characteristics of the three device types控制工程网版权所有, and that information would likely serve you in the majority of applications. Many articles have been written with this assumption. HoweverCONTROL ENGINEERING China版权所有, these generalizations don’t always apply, and technologies are evolving in a way that changes their relevance. We need to examine some of those points and see what we can draw from them. In preparing this article, I consulted with a variety of people, generally representing smaller companies for whom temperature measurement is a major, if not the largest partCONTROL ENGINEERING China版权所有, of their business activity.
　　Conventional wisdom?
　　When choosing a sensor控制工程网版权所有, there are several basic questions you have to as