KX Compensation Wire KX-H-YV Thermocouple Temperature Measurement Wire KC/SC/BC Type；

Section 1: Compensation Winding Working Principle

In a certain temperature range, wires with thermoelectric properties similar to those of thermocouples are called compensating wires for thermocouples. According to the intermediate temperature rule of thermocouples, the total electromotive force value of the thermocouple temperature measuring circuit is only related to the temperatures of the hot junction and the reference junction, and is not affected by the change in intermediate temperature, so compensating wires that match the thermocouple material can be used to replace the expensive thermocouple material that needs to be extended, extending the reference junction from the thermocouple terminal box to the instrument terminal, and compensating for the original reference junction temperature with the compensating wire. In addition to reducing measurement errors, compensating wires offer the following advantages: they can improve the physical and mechanical properties of the thermocouple temperature measuring circuit, such as using multi-strand cores or small-diameter compensating wires can enhance the flexibility of the circuit, making connections easier and more susceptible to shielding external interference; they can also reduce the cost of the measuring circuit.

II. Compensation Wire Classification

Extended and compensating types are differentiated by principle. The nominal chemical composition of the alloy wire in the extended type is the same as that of the thermocouple it is paired with, thus the thermoelectric potential is also the same, indicated by "X" in the model. The compensating type has a different nominal chemical composition from the thermocouple it is paired with, but within its operating temperature range, the thermoelectric potential is close to the nominal value of the thermocouple's potential, indicated by "C" in the model. In terms of compensating accuracy, there are general-grade and precision-grade, with the precision-grade error after compensation generally only half that of the general-grade, commonly used in applications requiring high measurement precision. For example, for compensation wires with S, R scales, the precision-grade tolerance is ±2.5℃, and the general-grade tolerance is ±5.0℃; for K, N scale compensation wires, the precision-grade tolerance is ±1.5℃, and the general-grade tolerance is ±2.5℃. In the model, the general-grade is not marked, while the precision-grade is indicated by adding an "S". In terms of operating temperature, general-purpose types are typically used within 0 ~ 100℃ (some are 0 ~ 70℃), while heat-resistant types operate up to 0 ~ 200℃. Additionally, compensation wires can be categorized by the number of cores (single-core vs. multicore/soft wire), by whether they have a shielding layer (standard vs. shielded), and there are also compensation wires specifically for explosion-proof circuitry.

III. Several Issues in Application

1. Matching Compensation Wires with Thermocouples: Various compensation wires can only be used with thermocouples of the same scale to avoid undercompensation or overcompensation. The compensation electromotive force values required for commonly used thermocouples at 100℃ and 200℃ are listed in Table 1: Table 1 - Compensation Electromotive Force Values of Common Thermocouples at 100℃ and 200℃

Thermocouple Name, Thermocouple Type, Reference End Potential at 0°C mV, at 100°C, at 200°C

Platinum Rhodium 10 - Platinum S 0.646 1.441 Platinum Rhodium 13 - Platinum R 0.647 1.469 Platinum Rhodium 30 - Platinum Rhodium 6 B 0.033 0.178 Nickel Chrome - Nickel Silicon K 4.096 8.138 Nickel Chrome Silicon - Nickel Silicon N 2.774 5.913

Nickel-Chromium—Nickel-Copper E 6.319 13.421 Iron—Nickel-Copper J 5.269 10.779 Copper—Nickel-Copper T 4.279 9.288

When using a compensation wire with a K degree of accuracy paired with a thermocouple of N degree accuracy, overcompensation will occur, resulting in a displayed temperature that is too high; conversely, using a compensation wire of N degree accuracy with a thermocouple of K degree accuracy will lead to undercompensation, causing the displayed temperature to be too low.

KX Compensation Wire KX-H-YV Thermocouple Temperature Measurement Wire, KC/SC/BC Models