Water-Tree Resistance Evaluation Using Molded Electrode Holes
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Solution Overview
Problem
The existing methods for reproducing the water-tree phenomenon in insulation materials for rotary electric machines are time-consuming, which delays product development and cycle time due to shape variations in electrode holes affecting the molecular structure and making it difficult to replicate actual insulating cable conditions.
Innovation Solution
A water-tree resistance evaluation method that involves applying voltage to a test piece with conically tapered electrode holes formed using a mold to accurately replicate the water-tree phenomenon, reducing the reproduction time by ensuring consistent electrode hole shapes and minimizing damage to the insulation material.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protruding portions are pushed into the XLPE plate to form electrode holes, then water trees can be reproduced near the electrode holes, but the electrode holes vary in shape and damage the molecular structure of the XLPE
Solution Approach 1:
The patent uses a mold member with concave portions that are negative impressions of the desired electrode hole shape. By pushing this mold into the XLPE plate, electrode holes with consistent and accurate shapes are formed, copying the mold's precise geometry rather than relying on direct protrusion formation which causes shape variation.
Solution Approach 2:
The patent replaces the direct mechanical pushing method with a mold-based system. Instead of pushing protruding portions that directly contact and damage the XLPE, a mold with concave portions is used to form the electrode holes, substituting the harmful direct mechanical action with a controlled molding process that preserves the molecular structure.
2Productivity
If the molecular structure of XLPE around electrode holes is damaged by pushing protruding portions, then electrode holes can be formed quickly, but the water trees reproduced do not accurately represent actual insulating cable conditions
Solution Approach 1:
The mold member with concave portions serves as a negative copy of the desired electrode hole geometry. This copying approach allows rapid formation of multiple identical electrode holes without manual adjustment, maintaining both high productivity and accurate reproduction of water tree phenomena that match actual cable conditions.
Solution Approach 2:
The mold member is pre-formed with the exact concave geometry needed for accurate electrode hole formation. This preliminary preparation of the mold allows subsequent electrode holes to be formed quickly and consistently without repeated adjustments, achieving both speed and accuracy in the water tree reproduction process.
3Ease of manufacture
If electrode holes are formed by pushing protruding portions into the XLPE plate, then the test setup can be completed efficiently, but the shape variation of electrode holes complicates the evaluation of water trees
Solution Approach 1:
The mold member with concave portions is a pre-fabricated copy of the desired electrode hole geometry. By using this mold, multiple electrode holes can be formed efficiently with consistent shapes, eliminating the need for complex post-processing or adjustment procedures that would otherwise be required to compensate for shape variations.
Solution Approach 2:
The patent changes the geometric parameters of the electrode hole formation process by using a mold with predetermined concave dimensions. This parameter control ensures that all electrode holes have identical shapes and sizes, simplifying the evaluation process by eliminating shape variation as a confounding factor in water tree assessment.
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 method significantly shortens the water-tree phenomenon reproduction test time, allowing for more reliable insulation design and faster product development by ensuring consistent and accurate evaluation of water-tree resistance, leading to improved insulation performance in rotary electric machines.
Implementation Method 1
The water trees is a kind of an insulation deterioration phenomenon that occurs in the insulating material of the insulating portion, which is triggered by an electric field being applied to the insulating portion in the case that water coexist for a long time.
Implementation Method 2
a relatively high electric field is generated near each electrode hole
Data Source
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AI summary
To shorten the reproduction time required in the water-tree phenomenon reproduction test, a water-tree resistance evaluation method has: a material selection step (S110) for selecting a candidate insulation material; a test step (S120) for carrying out a water tree test on a test piece having electrode holes formed on a first surface; and a candidate insulation material evaluation step (S130) for evaluating characteristics of the candidate insulation material, including progress and speed of a water tree. The test step (S120) includes: a system and condition setting step (S121) for setting a test system so that the first surface of the test piece is immersed in an application-side aqueous solution of a voltage application side while a flat second surface of the test piece, which is an opposite side from the first surface, is immersed in a ground-side aqueous solution; a voltage application step (S122) for grounding a ground-side electrode that is immersed in the ground-side aqueous solution, while applying an AC voltage to an application-side electrode that is immersed in the application-side aqueous solution; a measurement step (S123) for measuring progress of water tree inside the test piece at predetermined intervals; and a period determination step (S124) for determining whether a test period has exceeded a predetermined period.