Compensating Wire KX-YP2VP2 Copper Strip Shielded Thermometer Wire KCSCEXJX Type；

I. Working Principle of Compensation Wire

Thermocouple compensating wires are conductors with thermoelectric properties similar to those of thermocouples within a certain temperature range. According to the intermediate temperature rule for thermocouples, the total electromotive force (emf) of the thermocouple temperature measurement circuit is only related to the temperatures of the hot and reference junctions, unaffected by changes in the intermediate temperature. Therefore, compensating wires that match the thermocouple material can 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 measurement circuit, such as using multi-strand cores or small-diameter compensating wires can increase the flexibility of the circuit, making connections easier and more susceptible to shielding against external interference; they can also reduce the cost of the measurement circuit.

Part II: Compensation Wire Classification

Extended type and compensating type are divided based on 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, hence the electromotive force is identical, and it is indicated with an "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 electromotive force is nearly the same as the nominal value of the thermocouple's electromotive force, and it is indicated with a "C" in the model. In terms of compensation accuracy, there are general-grade and precision-grade options, with the precision-grade compensation error generally only half that of the general-grade, commonly used in high-precision measurement applications. For example, for compensation wires with S and R scales, the precision-grade tolerance is ±2.5°C, and the general-grade tolerance is ±5.0°C; for K and N scale compensation wires, the precision-grade tolerance is ±1.5°C, and the general-grade tolerance is ±2.5°C. In the model, the general-grade is not indicated, while the precision-grade is indicated by adding an "S". From the perspective of operating temperature, there are general-purpose and high-temperature-resistant types, with general-purpose operating temperatures of 0 ~ 100°C (some are 0 ~ 70°C), and high-temperature-resistant operating temperatures of 0 ~ 200°C. Additionally, compensation wires can be categorized by the number of cores (single-core or multi-core/soft wire) and by whether they have a shielding layer (standard or shielded). There are also compensation wires specifically designed for explosion-proof circuits.

III. Several Issues in Application

1. Matching Compensation Wires with Thermocouples: Compensation wires of various grades can only be used with thermocouples of the same grade. Otherwise, there may be undercompensation or overcompensation. The thermal electromotive force (EMF) values for commonly used thermocouples at 100℃ and 200℃ are listed in Table 1: Table 1 Thermal EMF Values of Common Thermocouples at 100℃ and 200℃

Thermocouple Name | Thermocouple Type | Reference End at 0℃ | Thermal EMF at 100℃ | 200℃

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

When using compensation cables with a K-type temperature difference and thermocouples with an N-type temperature difference, over-compensation occurs, resulting in a higher displayed temperature; conversely, using N-type compensation cables with K-type thermocouples leads to under-compensation, showing a lower temperature.

Compensating Wire KX-YP2VP2, Copper Tape Shielded Temperature Measuring Wire KCSCEXJX Type