When connections are taken from thermocouples to instruments situated at remote locations either by permanent wiring or flexible cables, it is essential to use the materials having the same EMF output as the thermocouple combination to avoid spurious EMFs generated in the cables. In order to solve this problem, it is a general practice to use the alloys of same composition but calibrated in lower temperature ranges. These lead wires are called Thermocouple ExtensionWires and are distinguished by an additional letter ‘X’ viz: Isatherm Plus® KPX and Isatherm Minus® KNX.
Isatherm Plus® and Isatherm Minus® are Registered Trademarks of Isabellenhuette Heusler GmbH & Co. KG, Germany