thermocouple
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How is compensation achieved inside the thermocouple chamber, and how is it configured in the DCS?
The input module has automatic temperature compensation components.
Our connectors here come with compensation; the compensation wire is connected directly to the connector terminals
There is a setting in the DCS hardware configuration; it’s usually located on the card, and you just need to select it in the hardware settings
The clamps for thermocouples all have compensation elements, usually a black one that is connected to the lowest part of the clamp
Both instruments and DCS systems measure the temperature within the sensor cards or instruments, which is used for cold-end mechanical compensation. The compensation is carried out automatically by the software; for some cases, it is possible to set no compensation
Typically, a DCS system includes a temperature compensation module, which functions similarly to an RTD module; a small PT100 sensor is connected to it in order to measure the temperature inside the cabinet. This temperature serves as the reference temperature. The principle behind this is simple: the compensation wire of a thermocouple is used to extend the reference terminal (the cold end) into the cabinet. Without such a compensation wire, the cold end would be at the ambient temperature outside the cabinet. To obtain accurate readings, it would be necessary to place a thermal resistor next to each thermocouple in order to measure the ambient temperature, which is quite cumbersome.
The compensation of thermocouples relies on the wiring method; a 4-wire system along with a Wheatstone bridge is used for compensation.