Why would one need different Thermoelement connector for different type

[RoadRunner]

I have recently bought a rusty broken, Digistant Temperature sensor calibrator off ebay, it came with many different connectors as per image.

Why would one need different connector?

[wizard69]

Thermocouples are created any time dissimilar metals come into contact.    Also there is the concept of reference junction compensation.

The NIST as some create materials related to temperature transducers.

[elekorsi]

as written above, thermocouple junction occurs when two different metals are joined. For that reason there are different connectors for different thermocople types, so that there are no additional TC joints. Also the connecting cables must be specified specifically for the TC type that is used...forget regular copper cables. Same goes for any terminals in the cabinet...