Moisture Sensor with Pleated Case for SF6 Gas
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Solution Overview
Problem
Conventional moisture concentration detecting devices in gas insulating devices face measurement errors due to contamination from decomposition products of SF6 gas, leading to inaccurate AC impedance readings and moisture concentration measurements.
Innovation Solution
A moisture concentration detecting device with a gas chamber, porous electrodes, a solid electrolyte membrane, a pleated case, and a storage device that corrects AC impedance measurements using conversion information to account for contamination effects, ensuring accurate moisture concentration readings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the moisture sensor is used to detect moisture concentration in SF6 gas, then the moisture concentration can be measured, but the surface of the sensor becomes contaminated by decomposition products, causing measurement errors
Solution Approach 1:
The patent introduces a separate gas introduction path that allows gas to be introduced into the sensor from the outside of the gas insulating device rather than directly from inside. This segmentation isolates the sensor from direct exposure to decomposition products while still enabling moisture concentration measurement through the introduced gas.
Solution Approach 2:
The patent uses an intermediate gas introduction mechanism that mediates between the SF6 gas environment and the moisture sensor. By introducing gas through a separate path and controlling the introduction conditions, the sensor is protected from direct contamination while still detecting moisture concentration accurately.
2Measurement precision
If the AC impedance measurement is performed to detect moisture concentration, then the moisture level can be detected, but the leakage current on the sensor surface increases due to contamination, causing measurement errors
Solution Approach 1:
The patent extracts the gas introduction function from the direct internal environment and creates a separate introduction path. This allows the AC impedance measurement to be performed on gas that has been introduced under controlled conditions, separating the measurement function from the harmful internal environment that generates leakage current.
Solution Approach 2:
The controlled gas introduction path acts as an intermediary that enables AC impedance measurement while protecting the sensor surface from conditions that generate leakage current. The intermediate mechanism allows measurement without direct exposure to harmful factors.
3Speed
If the moisture sensor element is placed inside the gas insulating device, then direct detection is possible, but the sensor surface becomes contaminated by decomposition products from arc generation
Solution Approach 1:
The patent segments the detection system into two parts: the moisture sensor that remains protected outside the gas insulating device, and the gas introduction path that brings gas samples to the sensor. This segmentation maintains fast detection capability while protecting the sensor from contamination by arc-generated decomposition products.
Solution Approach 2:
The gas introduction path serves as an intermediary that enables fast detection response without requiring the sensor to be physically placed inside the gas insulating device. The intermediate mechanism transports gas samples rapidly to the sensor while protecting it from harmful decomposition products.
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 device provides high-accuracy moisture concentration measurements by reducing the impact of contamination and enhancing measurement precision through impedance correction and increased surface area for reduced leakage current effects.
Implementation Method 1
a hydrogen-ion conductive solid electrolyte membrane that is provided between the porous electrodes and is in equilibrium with the moisture concentration in an SF6 gas
Implementation Method 2
The moisture concentration detecting devices measure the moisture concentration in the SF6 gas by applying an AC voltage across the porous electrodes and measuring the AC impedance between the electrodes
Data Source
AI summary
A moisture concentration detecting device including a gas chamber; a pair of porous electrodes facing each other in the gas chamber; a solid electrolyte membrane sandwiched between the electrodes; a case which covers the electrodes and the solid electrolyte membrane and on a surface of which a pleated portion is provided; an impedance measuring circuit measuring an AC impedance between the electrodes by applying an AC voltage to the electrodes; a storage device storing therein conversion information for converting an AC impedance between the electrodes into a moisture concentration in the insulating gas; and a computing unit obtaining a moisture concentration in the insulating gas from a measured value of the AC impedance by referring to the conversion information stored in the storage device with respect to the measured value of the AC impedance input from the impedance measuring circuit.