Thermocouples are sensors used to measure temperature. The main components of thermocouples are a thermocouple element, which generates what is known as thermoelectric voltage, and a connector, such as a plug. Thermocouples are used in many areas of temperature measurement. They are characterized by their highly flexible design and fast response time.
Overview of Thermocouples
The following thermocouples are defined in ISO EN 60584-1:
| Type | Positive Connection [plus] | Negative Wire [minus] | Color DIN [plus / minus] | Temperature range [°C] |
|---|---|---|---|---|
| R | PtRh13% | Pt | orange / white | 0 +1600 |
| S | PtRh10% | Pt | orange / white | 0 +1600 |
| B | PtRh30% | PtRh6% | gray / white | +600 +1700 |
| J | Fri | CuNi | black / white | -200 +750 |
| T | Cu | CuNi | brown / white | -200 +400 |
| E | NiCr | CuNi | violet / white | -200 +900 |
| K | NiCr | NiAl | green / white | -200 +1100 |
| N | NiCrSi | NiSi | pink / white | -200 +1200 |
| C | WRe5% | WRe26% | red / white | 0 +2200 |
| A | WRe5% | WRe20 | red / white | 0 +2200 |
Various combinations of metals and alloys have proven to be advantageous because they exhibit an almost linear relationship between stress and temperature.
It is important to know that the thermoelectric voltage does not originate at the tip. The voltage is generated between the two wires. Most of the stress occurs in the area where the temperature difference is greatest, for example, at the transition from the furnace chamber to the insulation.
We have compiled more details in the article Thermal voltage.
