Views: 0 Author: Site Editor Publish Time: 2022-04-06 Origin: Site
Thermocouples are sophisticated devices used to measure the temperature in various applications, from kilns, to cold storage, to diesel engines. The critical nature of these devices means they require high-quality wiring inside. Otherwise, the readings could be incorrect, leading to varying problems.
A thermocouple consists of two dissimilar metal wires coming together to create a temperature measurement junction. Heating the connection point of both metals creates a thermoelectric current known as a Seebeck current. As the heat transfers from the hot end to the cooler end, the electrons within the metals create electricity.
For a thermocouple to function correctly, one metal must be positively charged and the other negatively charged. An example would be positively charged copper on one wire and negatively charged nickel on the other.
Thermoelectric currents are minuscule, typically measuring in microvolts. That voltage then gets translated into temperature readings. Thermocouple readouts can be quite precise, which is why these devices hold value in so many unique applications.
A thermocouple is made up of multiple components. Here is a breakdown of each piece.
A measuring junction is the “hot” end of the thermocouple. This junction is where the two wires meet, and where temperature is measured. There are three kinds of measuring junctions:
· Exposed junction – Nothing protects the wire ends, meaning that they can rust or get damaged over time.
· Grounded junction – A metal sheath covers the wires (usually stainless steel). This design is much more stable and long-lasting.
· Ungrounded junction – In this case, the sheath is not connected electrically to the wires. An ungrounded junction is less susceptible to electromagnetic interference.
The reference junction is the other side of the thermocouple, or the “cold” connection. To get an accurate thermocouple readout, you need to know the wires’ temperature at rest—hence the term “reference.” The reference junction is often built into the display instrument, so the user won’t even see it.
Since thermocouples are often placed in conditions not suitable for people, such as extreme cold or heat, the temperature reader often gets placed a significant distance away from the measuring junction. To ensure the accuracy of the readout, these systems use extension wires. These wires are insulated and protected so that the voltage isn’t affected by other environmental factors. The wires are never calibrated above 204°C to ensure stability.
Fongming Cable Factory, high temperature wire and cable manufacturer.