Mineral-Insulated Flame Sensor Cable for 300°C Signal Integrity
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Solution Overview
Problem
Existing flame sensor cable assemblies for turbines fail to maintain insulation resistance at high temperatures near combustion chambers, leading to potential fuel feed issues if the ignition flame is extinguished.
Innovation Solution
A triaxial cable assembly with three conductive layers and two insulating layers, utilizing mineral insulation materials like magnesium oxide and ceramic materials to withstand temperatures above 300 degrees Celsius, ensuring electrical insulation and signal integrity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cable insulation materials are used in flame sensor cable assemblies, then the cable assembly can be manufactured with standard materials and processes, but the insulation resistance is lost at high temperatures near combustion chambers
Solution Approach 1:
The patent changes the material parameter from conventional insulation materials to magnesium oxide mineral insulation material, which fundamentally alters the temperature resistance characteristics. This material substitution enables the cable to maintain insulation resistance at temperatures above 300°C where conventional materials would fail.
Solution Approach 2:
The cable assembly uses a composite structure combining magnesium oxide mineral insulation material with metal conductors and protective sheathing. This composite construction provides both electrical insulation and high-temperature resistance, resolving the contradiction between maintaining insulation properties and withstanding extreme temperatures.
2Measurement precision
If the cable assembly is positioned close to the combustion chamber for signal detection, then flame detection accuracy is improved, but the cable is exposed to temperatures that cause insulation failure
Solution Approach 1:
By changing the insulation material parameter to magnesium oxide, the cable can physically withstand the high temperature environment near the combustion chamber, enabling close positioning for accurate flame detection without suffering thermal damage to the insulation.
3Ease of manufacture
If standard cable materials are used to reduce cost and simplify manufacturing, then manufacturing complexity is reduced, but the cable cannot withstand temperatures above 300 degrees Celsius
Solution Approach 1:
The patent specifies magnesium oxide mineral insulation material as a standard component, changing the material parameter to achieve both high-temperature resistance and manufacturing feasibility. This material is available as a standardized component that can be manufactured using established processes.
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
The cable assembly effectively maintains insulation resistance and signal integrity at high temperatures, enabling timely shutdown of fuel feed in case of a flame-out condition, thus preventing un-combusted fuel buildup and ensuring safety and efficiency in turbine operations.
Implementation Method 1
The cable assembly includes a first insulating layer circumferentially surrounding the inner conductor. The first insulating layer includes a mineral insulation material, such as magnesium oxide
Implementation Method 2
utilizing mineral insulation materials like magnesium oxide and ceramic materials to withstand temperatures above 300 degrees Celsius, ensuring electrical insulation and signal integrity
Data Source
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AI summary
A cable assembly for a flame sensor apparatus includes an inner conductor electrically connected to a photodiode that generates a current. The inner conductor transmits the current from the photodiode. A first insulating layer circumferentially surrounds the inner conductor. The first insulating layer includes a mineral insulation material. An inner sheath circumferentially surrounds the first insulating layer. The inner sheath includes an electrically conductive material. A second insulating layer circumferentially surrounds the inner sheath. The second insulating layer includes a mineral insulation material. An outer sheath circumferentially surrounds the second insulating layer. The outer sheath includes an electrically conductive material. The cable assembly is for use in temperatures up to about 300 degrees Celsius or greater. A method of attaching a cable assembly for a flame sensor apparatus is provided.