Thermocouple Wire that is used in a thermocouple from the point of sensing to the point of cold junction compensation (cjc end) where the signal is measured.
A thermocouple is a sensor for measuring temperature, that consists of two dissimilar metals that are joined together at the sensing end. Different thermocouple types (e. G. J, K, T, E, etc) use different mixtures of metals in the wire. At the cjc end, the millivolt value provided by the thermocouple represents the difference in temperature of the sensing end as compared to the cjc end (also called the reference end).
Cable Colours, you need to consult a cable colour coding guide like this one. R.J. Cables or this one T.C. colour codes
Yellow does infact refer to a K type thermocouple extension cable as opposed to Brown which is for a K type thermocouple compensating cable.
Cable types, THERMOCOUPLE EXTENSION & COMPENSATING CABLES R.J. Cables
Thermocouple extension & compensating cables, transmits, the cold junction of temperature sensor installed at the measuring point to the measuring instruments installed at remote location in control room.
Extension cables are made from the same metals used in thermocouples, but for compensating cable, materials of similar thermoelectric properties as of thermocouple in use, are employed to reduce the cost.