Extended Reach With Premium Thermocouple Wires

Thermocouple sensors use dissimilar metals to convert heat into an electromagnetic field that generates voltage, which can then be related to temperature based on their relationships between metals.

Extension cables complete the thermocouple circuit between instrumentation that reads it and its point of origin, the thermocouple itself. Selecting appropriate insulation and jacket materials can ensure accurate temperature readings even over long distance runs.

Thermocouple Wire Types

Industrial applications often call for thermocouple wires to be extended from their cold junction to an instrument that reads it, using extension-grade wire. Care must be taken in selecting extension wire metals as failure to match exactly may produce different measurements than expected and result in inaccurate temperature readings.

A type K thermocouple is often the go-to choice, featuring nickel-chromium and constantan as its positive and negative leads respectively. It provides reliable performance across most environments and operates over a broad range of temperatures; typically selected for use in environments involving mild oxidizing, mildly reducing and cryogenic temperatures as well as harsh environments – for those in which protection from contamination may be an option, metal tubes can sometimes be added at its reference junction to protect its performance further.

Thermocouple Wire Alloys

California Fine Wire’s selection of thermocouple alloys including alumel, cuprum, copel and chromel can help customers select the one most suited for their application.

Nickel-based alloys like 405 and 426 alloys provide significant advantages when it comes to compensating lead wires; their engineered shape closely follows thermocouple emf curves up to 1600degF.

These alloys also boast superior ductility and resistance to oxidation across a broad temperature range, making them suitable for long duration applications that require stability and accuracy. Plus, these alloys meet ASTM Standard E230 which includes calibration tables, color codes and assigned letter designations.

Thermocouple Wire Lengths

Temperature sensor probes may be located a considerable distance from their measuring instrument, so to get their signal back you’ll require an extension wire made of premium metals similar to that found in thermocouples. There are various length options and metal types for these wires – using standard copper wiring or terminal blocks instead can introduce cold junctions that increase measurement error and cause further disruptions of circuit integrity.

At the core of all thermocouple cable installations lies keeping them free from electromagnetic fields. Low voltage signals produced by thermocouples generate noise that may pick up on electrical power lines, motors or any other sources of interference nearby.

Loop resistance should also remain below 100 ohms; this can be determined by multiplying cable resistance per double feet with its total length (remember, each foot of run includes one wire of your thermocouple circuit) to determine its total resistance.

Thermocouple Wire Accuracy

Thermocouples are simple temperature measurement sensors based on the Seeback Effect. Different metals are joined at their tip to form the thermocouple and, when exposed to temperature gradients, a voltage is produced which corresponds with measured temperatures.

As each thermocouple’s metal composition corresponds with specific temperature ranges, it is imperative that its extension wire be of identical composition for accurate measurements. Failure to do this may introduce signal errors due to dissimilar metal junctions that arise between different wires.

To avoid this issue, extension wires made from conductors with similar thermoelectric characteristics provide a cost advantage and keep polarity of thermocouples correct over long run lengths by marking positive legs with color codes matching thermocouple types – this helps ensure correct polarity for accurate operation and reduced errors over long distances.