Three-Wire Temperature Probe Resistance Equalization
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Solution Overview
Problem
Existing three-wire temperature probes experience measurement inaccuracies due to unequal resistances in the connecting wires, particularly in long cables, which cannot meet the required accuracy classes for temperature measurement.
Innovation Solution
A temperature probe design that compensates for resistance differences in connecting wires by inserting conductive elements made of a higher resistivity material, such as Constantan, into two of the three wires, ensuring equal resistance in all connecting lines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-wire connection is used to reduce cable costs and complexity, then the number of wires is reduced and cable diameter is decreased, but measurement accuracy deteriorates due to unequal resistance in connecting wires
Solution Approach 1:
The patent changes the resistance parameter of connecting wires by inserting conductive elements with different resistivities (e.g., Constantan) into two of the three wires. This allows equalizing the total resistance of all three connecting wires, thereby eliminating the measurement error caused by unequal wire resistances while maintaining the cost-effective three-wire configuration
Solution Approach 2:
The patent introduces conductive elements as intermediary components inserted into two of the three connecting wires. These intermediaries have higher resistivity than the original copper wires and are specifically selected to compensate for resistance differences, enabling accurate temperature measurement in the three-wire configuration
2Use of energy by moving object
If copper wires are used in long cables, then electrical conductivity is high, but resistance differences between wires become significant and cause measurement errors
Solution Approach 1:
The patent modifies the resistance parameter of the connecting wires by inserting conductive elements made of materials with different resistivities. This compensates for the inherent resistance differences in long copper wires, allowing accurate temperature measurement while maintaining the electrical conductivity benefits of copper
3Measurement precision
If conductive elements with higher resistivity are inserted into connecting wires, then resistance equalization is achieved and measurement accuracy is improved, but device complexity and manufacturing steps increase
Solution Approach 1:
The patent applies preliminary action by pre-calculating and pre-selecting conductive elements with specific resistivity values and dimensions before cable assembly. This allows the resistance equalization to be built into the cable structure during manufacturing, eliminating the need for field adjustments and simplifying the overall device complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Achieves high accuracy temperature measurements by equalizing the resistances of the connecting wires, meeting Class A or B accuracy standards even in long cables.
Implementation Method 1
the resistivity of said second material is greater than the resistivity of the first material, and wherein the inserted conductive elements are designed in such a way that the second connecting line and the third connecting line have substantially the same resistance as the first connecting line
Data Source
AI summary
A temperature probe for determining the temperature according to the three-point probe method includes a three-wire line several meters long consisting of a first connecting line, a second connecting line, and a third connecting line connected to sensor element. The connecting lines are made of a first material and serve to transmit energy and the measured temperature values. A conductive element made of a second material is inserted in the second connecting line and in the third connecting line. The resistivity of said second material is higher than the resistivity of the first material. The two inserted conductive elements are designed such that the second connecting line and the third connecting line have the same resistance as the first connecting line. Additionally, the present disclosure refers to a method describing the manufacture of a temperature probe.