Why would anyone choose thermocouple instead of RTD?

Often asked & other; My temperature or environmental testing application is the best temperature sensor? ” The answer might be different, but the two main leader of the packaging is RTD ( Resistance temperature detector) And the second is the thermocouple. If you are looking for the best short answer, it is the RTD, but there is more to the story

the main reason for the RTD is best:

better long-term stability and more linear response, more gain - For a given temperature changes more signal, they were also more likely to lead connection management.

so why would anyone choose thermocouple instead of RTD?

is advantageous to the thermocouple position:

- the first reason Thermocouple is cheaper. The market demand usually require cheaper. Thermocouple is usually keep violent vibration or thermal shock environment better. They are usually more suitable for induction, rather than induction larger area or the temperature. 。

a step back: more balance, but these are the main factor. It's fair to say that there are other feasible temperature sensor can be used in many applications, but first is brief history courses. German physicist Thomas johann seebeck for the first time in 1821 found that any connection of different metals will generate potential related to the temperature. Therefore, by coupling two metals in the name of the equipment operation temperature. The result was the first electronic temperature sensing device, it can be designed to work in the absence of any external power supply. A few questions about how the sensors work is:

1) The careful control of the sensor used in metal type must be continued until a measuring instrument for temperature.

2） Need extra thermocouple as a fixed reference instrument itself. Due to the fixed reference temperature change often, so usually use extra RTD or band gap sensor to compensate the thermocouple calibration.

William & bull; Sir Siemens in 1871 found that the resistance temperature probe or RTD. He found that the platinum wire and other materials in temperature and has a clear relationship between the resistance of the material. The relationship between the temperature and the ohm than the thermocouple and the relationship between the voltage and temperature is more linear and easier to use.

thermal resistor is a special type of RTD, usually made of polymer or cheaper than Platinum materials. They usually have a narrow temperature range and has lower accuracy over a long period of time. As a side note, other thermistor usually but not always has a negative temperature coefficient ( NTC） As the temperature increases, which means that their has less resistance. This feature makes it suitable for a variety of special compensation application, such as offset with the temperature rise of other factors.

band gap, Transistor) Sensor is a significant, modern temperature sensor. The effect of the device using known, which is the base to emitter transistor voltage directly affected by temperature and predictable. Although these devices are seldom used in applications such as room temperature, but they are very cheap and can be easily integrated into other silicon circuit, makes the internal components temperature sensor is very simple and the price is reasonable. Their availability is mainly limited to - The range of 40 ℃ to + 200 ℃.

RTD is widely accepted as a long-term repeatability of the preferred temperature sensor. My position is that they will continue to be a & other; The best quality sensor & throughout; An advantage, but I do hear some interesting story, about the recent improvements in manufacturing and reads the thermocouple techniques. I think the jury is still out, but I would like to know others to experience A new generation of thermocouple and the accompanying 24 bits A/D sensing circuit.

to finally, thermocouple type and there is some difference between different types of RTD. Thermocouple type must match the instrument configuration read type. In the same way, RTD must with the curve of the controller configuration ( Usually a DIN curve) Matching. In addition, the base of RTD resistance value must match the controller configuration ( Usually at 0 c to 100 ohms)