Transformer Insulation Aging via Floating Electrode Capacitance
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Solution Overview
Problem
Non-liquid immersed transformers face challenges in effectively evaluating the aging degree of their solid insulation, which affects their performance and maintenance, as the dielectric properties of materials like epoxy resin and polyester change over time.
Innovation Solution
A non-invasive method using floating electrodes to form capacitive elements within the transformer coils, allowing for the measurement of complex permittivity, enabling the assessment of insulation aging and predicting the remaining life of the transformer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid insulation materials (epoxy resin, polyester) are used to isolate turns in non-liquid immersed transformers, then the transformer achieves effective electrical insulation, but the dielectric properties of the insulation change over time due to aging, making it difficult to evaluate the aging degree
Solution Approach 1:
The patent introduces floating electrodes as intermediary elements that can be inserted into the solid insulation material without damaging it. These electrodes serve as mediators to establish capacitive coupling with the winding turns, enabling non-invasive measurement of dielectric properties. The electrodes allow access to the insulation's electrical characteristics while maintaining its integrity, thus solving the contradiction between effective insulation and measurability of aging.
Solution Approach 2:
The patent replaces direct mechanical contact measurement methods with electrical field-based measurement. Instead of physically probing or disassembling the insulation to assess its condition, the system uses capacitive coupling between floating electrodes and winding turns to measure dielectric properties electrically. This substitution enables non-invasive, in-situ monitoring of insulation aging without mechanical damage.
2Measurement precision
If floating electrodes are introduced in the solid insulation to measure dielectric properties, then the aging degree can be evaluated, but the transformer structure becomes more complex
Solution Approach 1:
The patent divides the measurement system into modular floating electrodes that can be independently positioned at different locations within the insulation. Each electrode forms a separate capacitive element with corresponding winding turns, allowing segmented measurement of different insulation regions. This segmentation enables precise localized aging assessment while keeping each measurement element simple and manageable.
Solution Approach 2:
The floating electrodes serve multiple functions: they act as measurement probes for dielectric properties, can be positioned at various locations for different measurement points, and work with any winding configuration. The same electrode design can be used throughout the transformer, providing a universal measurement solution that reduces overall system complexity despite adding measurement capability.
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
Facilitates maintenance and end-of-life predictions by accurately measuring the aging of different areas of the transformer insulation, improving the reliability and efficiency of non-liquid immersed transformer maintenance.
Implementation Method 1
At least a part of the conductive winding and the one or more floating electrodes form one or more capacitive elements, respectively
Implementation Method 2
The method relates to the measurement of electrical properties (e.g. the complex permittivity in the frequency spectrum) of the solid insulation
Data Source
AI summary
Non-liquid immersed transformers and methods of measuring aging degree of the transformers' insulation are disclosed. The transformers comprise a solid insulation inside the conductive coil and one or more floating electrodes in the solid insulation. At least a part of the conductive coil and the one or more floating electrodes may form one or more capacitive elements, respectively. An electrical parameter, e.g. complex permittivity, of the capacitive element is measured and the aging degree is calculated as a function of the electrical parameter measurement.