Purpose and precautions of using compensating wires

Compensation wires are a pair of insulated wires with the same nominal value as the thermoelectric potential of the matched thermocouple within a certain temperature range (0~100 ℃). They are used to connect the thermocouple and the measuring device to compensate for the errors caused by temperature changes at the connection point between them and the thermocouple. A wire with thermoelectric properties that are very similar to those of a thermocouple within a certain temperature range is called a compensating wire for the thermocouple. According to the intermediate temperature rule of thermocouples, the total potential value of the thermocouple temperature measurement circuit is only related to the temperature of the hot end and reference end, and is not affected by changes in the intermediate temperature. Therefore, a compensation wire that matches the thermocouple material can be used to replace the valuable thermocouple material that needs to be extended. The reference end is extended from the thermocouple junction box to the instrument junction terminal, and the original reference end temperature is compensated by the compensation wire.

Purpose of compensating wire use

(1) Move the reference end of the thermocouple from a high temperature location to a more stable ambient temperature.

(2) Save a significant amount of precious and rare metal materials used for manufacturing thermoelectric electrodes.

(3) The use of compensating wires facilitates installation and wiring.

(4) Replacing the thermoelectric electrode with a compensating wire with a thicker diameter and higher conductivity can reduce the resistance of the thermocouple circuit, facilitating measurement and automatic control.

When using compensating wires, the following points should be noted:

(1) Various compensation wires can only be used with corresponding models of thermocouples, which means that the thermoelectric characteristics of various thermocouples and the compensation wires used must be the same within the specified temperature range (O~100 ℃).

(2) The temperature of the compensation wire and thermocouple connection point shall not exceed the specified operating temperature.

(3) When connecting compensation wires, thermocouples, and instruments, the positive and negative poles must not be connected incorrectly, and the two pairs of connection points must be at the same temperature.

(4) The diameter of the compensating wire should be selected according to the line resistance requirements of the equipped instrument.