UV Flame Sensor Run-On Detection via Secondary Electrodes
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Solution Overview
Problem
UV flame sensors degrade over time, leading to false alarms due to 'run-on' conditions where the sensor indicates a flame's presence even after the flame is extinguished, and existing solutions fail to effectively detect this degradation.
Innovation Solution
A UV flame sensor system with a pair of secondary electrodes enclosed in a mesotube forms a breakdown chamber to detect run-on conditions, exposed to UV radiation through an aperture and energized continuously with a lower voltage, allowing for detection of breakdowns and false sensing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a UV sensor is used to detect flame presence, then flame detection capability is improved, but false alarms occur due to run-on conditions when the sensor degrades
Solution Approach 1:
The patent applies preliminary action by continuously monitoring the UV sensor's health status through a dedicated monitoring circuit that detects run-on conditions before they cause false alarms. The system proactively identifies sensor degradation by detecting spontaneous current flow between electrodes, allowing preventive measures to be taken before reliability deteriorates.
Solution Approach 2:
The patent introduces an intermediary monitoring circuit that acts as a mediator between the UV sensor and the alarm system. This intermediary circuit continuously checks for run-on conditions by detecting abnormal current flow, and only allows alarm signals to pass through when the sensor is confirmed to be functioning properly, thus preventing false alarms while maintaining accurate flame detection.
2Reliability
If additional electrodes are added to detect run-on conditions, then reliability is improved, but device complexity increases
Solution Approach 1:
The patent merges the run-on detection function with the existing UV sensor structure by integrating a monitoring circuit that uses the same electrode assembly. The monitoring circuit combines multiple detection functions into a unified system that continuously monitors for abnormal current flow without requiring separate physical sensor units, thus improving reliability while minimizing the increase in device complexity.
Solution Approach 2:
The patent applies universality by designing the monitoring circuit to perform multiple functions: it continuously monitors for run-on conditions, detects flame presence, and controls alarm output. The same electrode structure serves both as the primary UV sensing element and as the basis for health status monitoring, allowing one component to fulfill multiple roles and reducing overall system 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
The system effectively identifies and prevents false alarms by continuously monitoring for breakdowns and UV light presence, ensuring accurate flame detection and reducing sensor degradation issues.
Implementation Method 1
The performance of the UV sensor is known to degrade over time. It can therefore be important to monitor the performance or 'health' of the UV sensor to identify when performance of the sensor degrades. One mode of failure is the state where the current flow across the two electrodes occurs spontaneously without the presence of the ultraviolet light from the flame.
Implementation Method 2
CA825764 discloses an UV radiation detection system utilizing a glow discharge tube with a first pair of first electrodes which is sensitive to radiation energy within a restricted energy spectrum range
Implementation Method 3
A UV flame sensor for detecting a run-on condition in a flame detector tube is disclosed. The sensor comprises a pair of secondary electrodes that are enclosed in a mesotube to form a breakdown chamber in order to detect run-on conditions
Data Source
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AI summary
A UV flame sensor for detecting a run-on condition in a flame detector tube is disclosed. The UV flame sensor comprises a pair of secondary electrodes that are enclosed in a mesotube to form a breakdown chamber in order to detect the run-on condition. These secondary electrodes are exposed to UV through an aperture in a cathode plate and are energized continuously by a lower voltage. The mesotube is expected to break down when the run-on condition occurs. The secondary electrodes can be placed in the same gas environment as the main electrodes that may take different forms, shapes and locations.