Thermocouple Compensating Cables

When taking connection from a Thermocouple to Instruments which are some distance away, either by Permanent Wiring or Flexible Cable, it is essentials to use materials having the same EMF output as the Thermocouple combination else spurious EMF can be generated at the junctions.
The best solution is to use leads of the same alloys as the Thermocouple. These are usually called Extension leads and are supplied as “Extension lead quality”, normally reffered to as KX, JX, TX, AND EX. Where this solution would be too expensive, comparatively cheaper alloys of different types from the Thermocouple combinations are used. These combinations have an EMF matched as closely as possible to the Thermocouple alloys although the EMF of the individual legs is not usually the same.
These Materials are termed as Compensating leads and generally give adequate compensation for EMF’s generation junctions. Compensating Cables have, within a limited temprature range, the same Thermo Electric characteristics as the actual Thermocouple wires. Therefore, by using such Cables to interconnect between the Thermocouple connection head and the measuring instruments or cold junction compensators, the cold junction is relocated at the measuring instruments or cold junction compensators.
EXTENSION CABLES COMPOSITION OF THE ALLOYS 
KX + ve Nickel Chromium
- ve Nickel Aluminuim 
TX + ve Copper
- ve Copper Nickel Alloy 
JX + ve Iron 
- ve Copper Nickel Alloy 
EX + ve Nickel Chromium
- ve Copper Nickel Alloy 
COMPENSATING CABLES COMPOSITION OF THE ALLOYS 
VX (KXA) + ve Copper
- ve Copper Nickel Alloy 
WX + ve Iron 
- ve Copper Nickel Alloy 
Both VX and WX are compensating cables for KX 
RX + ve Copper
- ve Copper Nickel Alloy 
SX + ve Copper
- ve Copper Nickel Alloy 
BX + ve Copper
- ve Copper 
UX + ve Copper
- ve Copper Nickel Alloy 
(UX Only used where the interconnection tempratures is in the range of 0 to + 50 degree centigrade.)
EMF as per ANSI MC 96.1 and IS 8784 
Conductor material as per ANSI MC 96.1 and IS 8784. 
Colour code as per various international standards.