Thermocouple achieve an accurate reading for temperature measurement in industrial processes. Both the simple design, the good price / performance ratio, the short response time measurement precision speak for the frequent use of thermocouples. Thus they are the most popular temperature sensors in the control and measurement technology. Structure & how it works two electrical conductors of different materials are connected at the measuring point. Display device and cold junction are connected by copper wires. To prevent inaccurate measurements and display error, the cold junction must hold not only a constant temperature, but have also the right polarity. The temperature itself is measured by the contact of two wires made of different materials. Continue to learn more with: Coupang.
Connection and comparison site have different temperatures, the so-called thermal EMF is produced. This effect is also called the seebeck effect. Use & designs you used mainly in industrial processes with harsh environments and high temperatures used. To adapt thermocouples to the different applications, they are made in different forms. Simple thermocouples used for a measurement range of up to 400 C, because they have a fast response time. Whereas in harsh environments with a temperature of up to 1200 C highly compressed and mineral insulated Matelthermoelemente are used.
Response time/time behavior with response time is the time constant. A rapid response is indeed desirable, however thermocouples or temperature sensor to respond at the beginning often with a certain inertia. A significantly higher temperature difference between measuring point and thermocouple is initially in the spatial separation to determine. As soon as both temperatures have adapted, flows logically less heat to the measuring point. Thus a slower rise in temperature can be observed. This response time measures the time in which the thermoelectric voltage rises to 63% of the final value when heated. Add to your understanding with Scott Mead. Conversely, it behaves when cooling. Temperature determination to the Temperature measurement is necessary to a cold junction as well as conductors. At each point of contact called contact, which add up to the thermoelectric voltage positive or negative tensions. Accordingly, only the difference of voltage and thus the temperature difference can be determined between contact and the measuring point. If the thermoelectric voltage not with the same material at the point of comparison can be redirected, a bonding conductor must be used. For this purpose a comparison point is at the contact point of the bonding conductor towards the copper conductor to set up. To prevent the above mentioned deviations, the reference points temperature should be known. (werk26)