Moisture Sensor Shield for High-Gradient Insulation
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Solution Overview
Problem
Existing moisture detection sensors for power transformers are limited to neutral/low-gradient regions and fail to capture moisture dynamics in hot spot areas, such as the winding, due to the creation of partial discharges from electric field gradients.
Innovation Solution
An electrical device with a moisture sensor comprising a capacitor with a first and second electrode and a dielectric material, where the solid insulation system forms the dielectric material, and a shield member connected to the first electrode to reduce partial discharges, allowing for moisture detection in high electric field gradient regions, including hot spots, through capacitance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a moisture sensor is installed in high electric field gradient regions (hot spots), then moisture detection accuracy in critical areas is improved, but partial discharges occur due to the electric field gradient
Solution Approach 1:
The patent applies the equipotentiality principle by introducing a shield member that creates an equipotential field around the sensor electrodes. The shield member is positioned between the sensor and the high electric field gradient region, equalizing the potential distribution and eliminating the harmful partial discharges while allowing the sensor to operate in previously inaccessible high-gradient zones for improved moisture detection accuracy
2Measurement precision
If electrodes are placed close to windings for direct moisture measurement, then measurement precision is improved, but partial discharges are generated due to high electric field gradients
Solution Approach 1:
The patent employs the intermediary principle by introducing a shield member as a mediator between the sensor electrodes and the high electric field gradient environment near the windings. This shield member acts as a protective interface that allows the sensor to maintain close proximity to the windings for accurate moisture measurement while preventing the direct interaction that would cause partial discharges
3Measurement precision
If a solid insulation system is used as the dielectric material, then direct moisture measurement in the insulation system is achieved, but moisture migration to the sensor may be restricted
Solution Approach 1:
The patent applies the porous materials principle by incorporating a porous layer in the sensor structure that facilitates moisture migration from the solid insulation system to the sensor electrodes. This porous structure maintains direct contact with the insulation system for accurate measurement while providing pathways for moisture to reach the sensing elements
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
Enables accurate moisture detection in high electric field gradient regions, improving the capture of moisture dynamics in hot spot areas, such as inside windings, by using a shield member to reduce partial discharges and a meshed structure for moisture migration, providing a direct measure of moisture levels in the solid insulation system.
Implementation Method 1
the capacitance of the capacitor providing an indication of a moisture level in the dielectric material
Implementation Method 2
the solid insulation system forms the dielectric material
Implementation Method 3
The shield member forms an equipotential screen with the first electrode, which thereby reduces the risk of partial discharges
Implementation Method 4
The first electrode has a meshed structure configured to facilitate moisture migration to and from the dielectric material
Data Source
Figure 1~2
Figure 3~5
AI summary
An electrical device comprising: voltage carrying components, a solid insulation system (8) configured to electrically insulate the voltage carrying components, and a moisture sensor (2) configured to detect moisture in the solid insulation system (8), wherein the moisture sensor (2) comprises: a capacitor (9) having: a first electrode (3), a second electrode (5), and a dielectric material (7) arranged between the first electrode (3) and the second electrode (5), wherein the solid insulation system (8) forms the dielectric material (7), the capacitance of the capacitor (9) providing an indication of a moisture level in the dielectric material (7).