Posted 06 December 2008
Extension or Compensating - Do You Know The Difference?
Thermocouple cables are used for measuring temperature and attach to the back of the thermocouple probe. All thermocouple cables come as pairs and have a “type” so you can identify them for usage, types include Kx, Jx, KCB, Ex, Rx (and many more). Each conductor is manufactured from different metals to complete the circuit.
A type Kx cable has one conductor (or leg as they are sometimes called) made of Nickel/chromium and the other of Nickel/aluminium. Extension cables are referenced by suffixing the type with an “x” (Kx , Jx) and use the same metals as the probe to provide accurate signals cross the entire measurement range. This can be expensive; Rx has one conductor made from platinum!
Compensating cables are manufactured from metals with similar properties to the probe that are more cost effective. These cables may have limited measurement ranges but can provide substantial savings without loss of data in certain applications.
Compensating cable types: KCB (compensating for Kx) RCA (compensating for Rx), SCA (compensating for Sx). Ensure you specify the correct type to avoid disaster!