Thermocouple and Compensating Cables

Different metal pairs generate different emfs which is proportionate to the hot junction and the point where it is measured. Common combination of thermocouple metals and their applicabtions are

1. K-ChromeVAlumel-Most commonly used

2.T-Copper/Constantan-for low temperature & cryogenic applications

3.J-iron/Constantan-Used in reducing atmosphere.

4.E-Chromel/Constantan-Highest EMF output.

5.R-(Platinum-13% Rhodium) / Platinum & S-(Platinum-10% Rhodium) / Platinum-Very High Temperature measurements.

6. B--(Platinum - 30% Rhodium) / Platinum-Mainly used in glass industry. Different colour codes of cores and sheathing as per international practices are used to denote the various thermocouple cables. .

COMPENSATING CABLES

Extention Leads of different metals but having similar EME output between 0°C to 100°C connected between Thermocouple metals junction and the measuring instruments arc called Compensating Cables which are generally recommended as solid conductor leads.