Three-Wire Temperature Probe Resistance Balancing
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Solution Overview
Problem
Existing three-wire temperature probe methods struggle to maintain high accuracy due to resistance differences among the connecting wires, especially in long temperature probes, leading to measurement errors that exceed acceptable limits.
Innovation Solution
The solution involves inserting conductive elements made of a material with higher resistivity, such as constantan, into two of the three connecting lines of a 3-wire cable, ensuring that each connecting line has substantially the same resistance, thereby compensating for resistance differences and enhancing measurement accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a three-wire connection method 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 resistance differences among the connecting wires
Solution Approach 1:
The patent changes the electrical parameters (resistance values) of the connecting wires by inserting conductive elements with different resistivities. Specifically, it inserts a first conductive element with higher resistivity into the second connecting wire and a second conductive element with higher resistivity into the third connecting wire, thereby adjusting the total resistance of each wire to be substantially equal. This parameter adjustment compensates for inherent resistance differences and enables accurate temperature measurement using the three-wire method.
Solution Approach 2:
The patent introduces conductive elements as intermediary components between the sensor element and the evaluation electronics. These conductive elements act as mediators that balance the resistance values of the connecting wires. The first and second conductive elements serve as intermediate components that equalize the resistance paths, allowing the three-wire connection to function accurately despite variations in wire resistance.
2Length of moving object
If very long temperature probes are used to reach remote measurement zones, then the measurement range is extended, but measurement accuracy deteriorates due to increased resistance differences in connecting wires
Solution Approach 1:
The patent applies parameter changes by inserting conductive elements with specific resistivities into the connecting wires of long temperature probes. The first conductive element with higher resistivity is inserted into the second connecting wire, and the second conductive element with higher resistivity is inserted into the third connecting wire. This adjustment equalizes the total resistance of all three wires, compensating for the increased resistance differences that occur in very long probes and maintaining measurement accuracy.
3Ease of manufacture
If connecting wires with different resistances are used in three-wire method, then manufacturing flexibility is improved, but measurement accuracy deteriorates due to uncompensated resistance errors
Solution Approach 1:
The patent changes the resistance parameters of the connecting wires by inserting conductive elements with different resistivities. The first conductive element with higher resistivity is inserted into the second connecting wire, and the second conductive element with higher resistivity is inserted into the third connecting wire. This allows the use of connecting wires with initially different resistances while achieving equal total resistance through the inserted elements, thus maintaining manufacturing flexibility while ensuring measurement accuracy.
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
This approach effectively compensates for resistance differences among the connecting wires, thereby achieving high accuracy temperature measurements, even in very long temperature probes, and meeting stringent accuracy class requirements.
Implementation Method 1
the resistivity of said second material is at least five times higher than the resistivity of the first material, and wherein the length and/or diameter of the two inserted conductive elements is/are dimensioned 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
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention refers to a temperature probe (1) for determining the temperature according to the three-point probe method with a sensor element (2) providing temperature values, wherein a three-wire line (3) several meters long, consisting of a first connecting line (4), a second connecting line (5) and a third connecting line (6), is connected to the sensor element (2), wherein the connecting lines (4, 5, 6) are made of a first material and serve to transmit energy and the measured temperature values, wherein a conductive element (7, 8) made of a second material is inserted in each of the second connecting line (5) and the third connecting line (6), the resistivity of said second material is higher than the resistivity of the first material, and wherein the two inserted conductive (7, 8) elements are designed in such a way that the second connecting line (5) and the third connecting line (6) have substantially the same resistance as the first connecting line (4). Additionally, the invention refers to a method describing the manufacture of a temperature probe (1).