Thermocouple Array Impedance Testing for Failure Isolation
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Solution Overview
Problem
Existing temperature measurement systems in thermocouple arrays are susceptible to failure modes such as thermocouple drift, open-circuit failure, and short-circuit failure, which affect the accuracy of the entire system when one thermocouple fails.
Innovation Solution
A system and method for detecting failures in thermocouple arrays using an impedance determination circuit with a capacitor, a comparator circuit, and an excitation circuit, along with a continuity test circuit, to individually test each thermocouple and isolate failed ones, preventing their impact on system readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If thermocouples are arranged in a parallel array for temperature measurement, then the system can provide temperature readings from multiple locations, but the system becomes susceptible to failure modes such as drift, open-circuit failure, and short-circuit failure that affect the entire system's accuracy
Solution Approach 1:
The patent divides the thermocouple array into individually addressable segments by assigning unique binary address codes to each thermocouple through strategic placement of address elements (A1, A0) at different positions in the array. This segmentation allows the control circuit to selectively activate and monitor specific thermocouples, isolating failures to individual units rather than affecting the entire array, thus maintaining system reliability while preserving the ability to monitor multiple locations.
2Reliability
If individual thermocouple failure is detected and isolated, then system accuracy is maintained, but additional circuitry and control mechanisms are required to test and identify failed thermocouples
Solution Approach 1:
The patent implements a universal test circuit that can evaluate all thermocouples in the array using the same hardware infrastructure. The control circuit generates address codes that selectively activate any thermocouple in the array, and the same excitation and measurement circuits are reused for each thermocouple through multiplexing. This multi-functional approach allows comprehensive failure detection and identification without requiring separate dedicated test equipment for each thermocouple, thereby limiting the increase in device complexity.
Solution Approach 2:
The patent incorporates feedback mechanisms where the control circuit continuously monitors the electrical characteristics (voltage, current, impedance) of each thermocouple and compares them against expected values. When a deviation indicating failure is detected, the feedback loop triggers an identification sequence that activates only the failed thermocouple using its unique address code, allowing precise localization of the fault. This feedback-driven approach automates the diagnostic process, reducing the complexity of manual testing procedures.
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
Ensures accurate temperature measurements by isolating and identifying failed thermocouples, maintaining system integrity and accuracy even when individual thermocouples fail.
Implementation Method 1
an impedance determination circuit including a capacitor... a comparator circuit connected to the impedance determination circuit... an excitation circuit connected to the impedance determination circuit
Data Source
AI summary
A system for detecting a failure in a thermocouple array may comprise the thermocouple array. The thermocouple array may comprise a plurality of thermocouples. The system may comprise an impedance determination circuit. The impedance determination circuit may include a capacitor that has a capacitance equal to an expected capacitance of one of the plurality of thermocouples. The one of the plurality of thermocouples may be connected to test nodes of the impedance determination circuit. The system may comprise a comparator circuit connected to the impedance determination circuit, where the comparator circuit includes an amplifier and a comparator. The system may comprise an excitation circuit connected to the impedance determination circuit, where the excitation circuit includes a waveform generator and an amplifier.