Field Device Resistance Monitoring for Limit Temperature Exposure
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Solution Overview
Problem
Existing methods struggle to reliably detect and prove whether a field device in automation technology has been exposed to excessively high temperatures, especially for warranty claims after the fact.
Innovation Solution
A method and device using a resistive element with a reference resistance value, which changes irreversibly at a limit temperature, allowing detection of temperature exceedance by comparing recorded resistance values with a reference value, considering time and temperature corrections, and storing data for remote analysis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a field device is exposed to high temperatures during measurement operation, then the measurement function is maintained, but the resistance value changes irreversibly making it difficult to detect temperature exceedance
Solution Approach 1:
The resistance element serves dual purposes: it functions as part of the measurement circuit and simultaneously acts as a temperature indicator through its irreversible resistance change. The element monitors its own thermal exposure without requiring separate sensors or complex monitoring systems, enabling self-diagnosis of temperature exceedance conditions
Solution Approach 2:
The method utilizes the inherent parameter change (resistance value) of the resistance element in response to temperature exposure. By measuring the resistance value before and after measurement operations, the system detects temperature exceedance through this physical parameter change, converting thermal exposure information into an electrical measurement signal
2Measurement precision
If the resistance value is measured continuously during measurement operation, then temperature exceedance can be detected, but data storage and processing requirements increase
Solution Approach 1:
The method extracts only the essential information needed for temperature monitoring: the resistance value at specific time points (before and after measurement operations). Rather than storing continuous resistance data, the system selectively captures and stores only the critical measurement points, significantly reducing data volume while maintaining detection precision
Solution Approach 2:
The resistance value is measured and stored before the measurement operation begins, establishing a baseline for comparison. This preliminary measurement allows subsequent detection of temperature-induced changes without requiring continuous monitoring during the actual measurement process, reducing overall data storage requirements
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
Enables retrospective detection of temperature exceedance in field devices, enhancing reliability and accuracy by accounting for reversible and irreversible resistance changes, facilitating warranty claims and maintenance.
Implementation Method 1
the resistive element (2) undergoes an irreversible change in its resistance value (WW) when the limit temperature (GT) is exceeded
Implementation Method 2
the circuit arrangement (1) is designed to determine an electrical resistance value (WW) of the resistive element (2), wherein the resistive element (2) undergoes an irreversible change in its resistance value (WW) when the limit temperature (GT) is exceeded
Data Source
Figure 1a~2
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Figure 5
AI summary
The invention relates to a method for monitoring whether a limit temperature (GT) for an automation engineering field device (11) is exceeded during a measurement operation (MB), wherein a resistor element (2) is designed such that, where the limit temperature (GT) is exceeded, it experiences an irreversible change to its resistance value (WW), the method comprising the steps of: - providing a reference resistance value (RW) for the resistor element (2); - detecting that the limit temperature (GT) has been exceeded if an irreversible change in the resistance value (WW) of the resistor element (2) that is attributable to the limit temperature (GT) being exceeded is determined. The invention also relates to an automation engineering field device (11).