Self-Calibrating Dissolved Gas Analysis Using Moisture-Conditioned Reference Gas
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Solution Overview
Problem
Conventional optical gas analysis devices, such as IR-based and UV-based systems, are inadequate for measuring trace quantities of specific gases due to insufficient sensitivity and selectivity, leading to measurement drift issues in applications like dissolved gas analysis for electrical equipment, which requires frequent and costly calibration using consumable gases.
Innovation Solution
A method and apparatus for calibrating gas measurement systems using ambient air under distinct moisture conditions, obtained through a moisture sensor, to derive and process optical absorption measurements, allowing for regular on-site calibration and improved long-term accuracy without the need for compressed gas cylinders or manual handling of oil samples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional optical gas analysis devices are used to measure trace quantities of specific gases, then the basic gas detection function is provided, but the measurement sensitivity and selectivity are insufficient leading to measurement drift
Solution Approach 1:
The patent changes the physical parameters of the reference gas by controlling moisture content under different conditions. By measuring optical absorption at multiple moisture levels and deriving calibration parameters from these variations, the system achieves higher measurement precision for trace gases while compensating for drift through parameter-based calibration adjustments
Solution Approach 2:
The system implements feedback by continuously monitoring optical absorption measurements under varying moisture conditions and using these measurements to dynamically adjust calibration parameters. This feedback loop maintains measurement reliability by compensating for drift in real-time based on observed absorption pattern changes
2Measurement precision
If frequent calibration using consumable gases is performed to maintain measurement accuracy, then measurement precision is improved, but operational complexity and costs increase
Solution Approach 1:
The system performs self-calibration by using ambient air with controlled moisture conditions as the reference gas. The calibration process is automated and requires no external consumable gases or manual intervention, reducing operational complexity while maintaining measurement precision through self-generated calibration data
Solution Approach 2:
The reference gas system serves multiple functions: it provides both the calibration reference and the measurement baseline simultaneously. By using ambient air that can be conditioned to different moisture levels, the system eliminates the need for separate calibration gases and sample gases, simplifying the overall system architecture
3Measurement precision
If manual handling of oil samples and compressed gas cylinders is used for calibration, then calibration can be performed, but ease of operation deteriorates due to frequent manual intervention
Solution Approach 1:
The patent replaces mechanical handling systems (manual oil sample transfer, gas cylinder connection/disconnection) with an automated optical measurement system. The system uses electronic control to manage moisture conditions and automatically performs calibration calculations, eliminating the need for manual mechanical operations while maintaining calibration 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 enables regular, on-site calibration of IR-based gas measurement systems, enhancing long-term accuracy and reducing costs by eliminating the need for consumable gases and manual handling, while compensating for measurement drift and changes in optical system properties.
Implementation Method 1
optical absorption measurement system configured to use one or more electromagnetic energy sources to obtain optical absorption measurements associated with a gas sample
Implementation Method 2
infrared light (IR) and/or ultra-violet (UV) light, to detect and to obtain gas concentration measurements
Implementation Method 3
Photoacoustic Spectroscopy (PAS)
Data Source
AI summary
A self-calibrating dissolved gas analysis apparatus and associated method are described. The dissolved gas analysis apparatus includes an analyser having an optical absorption measurement system using one or more electromagnetic energy sources to obtain optical absorption measurements associated with a gas sample. An observed response of the optical absorption measurement system is derived at least in part by using the optical absorption measurement system to obtain optical absorption measurements for a reference gas under one or more distinct moisture conditions. The derived observed response is then processed to quantify deviations between the derived observed response and an expected response and the quantified deviations are used to compensate information associated with gas concentration measurements derived by the dissolved gas analysis apparatus.