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I wish I knew when do I use a thermocouple compensating cable!
When you use a thermocouple, you can connect it to your control system or transmitter in many ways. The simplest way uses an extension cable or compensating cable.
Extension cables use the same material as the thermocouple, so they send the emission-motive force (EMF) accurately. X marks the spot, or in this case, the extension cable. You can find this information on the cable’s description, such as “JX” on a cable for a type-J thermocouple.
On the other hand, compensating cables use cheaper materials than thermocouples. You get similar numbers on your EMF in a more limited range than with X cables. The letter C identifies compensating cables, such as RCA on a cable for a type-R thermocouple.
Some manufacturers recommend using C cables only to connect the sensor to the transmitter. Beyond that, the cable is less accurate than an X cable. Also, its conventional insulating material, often PVC, covers a smaller temperature range.
This video will tell you about temperature measurement: