Undulating Transformer Dome Structure for Tracking Resistance

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Solution Overview

Problem

Conventional dry type transformers with flat dome areas face issues of medium voltage tracking due to insufficient track path between taps, leading to increased epoxy usage and risk of cracks in harsh environments.

Innovation Solution

A dry type cast coil transformer with an undulation structure in the dome area, allowing for a greater track path between taps while using less epoxy, achieved through a molding process that orients voltage taps upwardly and minimizes epoxy volume, featuring a mold with undulation forming structures adjacent to tap connection bases.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the track path is increased by orienting taps downwardly or vertically to create bushings, then the electrical track path between taps is improved, but more epoxy is used than needed and the thick epoxy regions are prone to cracks

Engineering Contradiction:

Improveelectrical track pathVSAvoidepoxy volume

Core Design Contradiction:

ReliabilityVSQuantity of substance

Solution Approach 1:

The patent applies curvature by creating a domed surface on the transformer coil instead of a flat surface. This domed configuration naturally increases the electrical track path between taps while maintaining a compact structure that reduces epoxy volume, eliminating the need for excessive epoxy thickness that would cause cracking.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Solution Approach 2:

The patent transitions from a two-dimensional flat surface to a three-dimensional domed surface. This dimensional change allows the track path to be extended in the vertical dimension while keeping the horizontal footprint compact, thereby reducing the overall epoxy volume required while maintaining adequate track paths.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If more epoxy is used to fulfill coil requirements, then the coil insulation is improved, but the regions of unnecessary epoxy are prone to cracks due to large thickness

Engineering Contradiction:

Improvecoil insulationVSAvoidepoxy crack resistance

Core Design Contradiction:

ReliabilityVSStrength

Solution Approach 1:

The domed surface configuration optimizes epoxy distribution by eliminating flat, thick regions that are prone to cracking. The curved geometry ensures more uniform epoxy thickness while maintaining adequate insulation, thereby improving both reliability and crack resistance simultaneously.

Inventive Principle:

Principle #14Spheroidality (Curvature)

3Ease of manufacture

If the flat top surface is used in conventional dome area, then the manufacturing is simplified, but medium voltage tracking occurs between energized parts in harsh environments

Engineering Contradiction:

Improvedome structure manufacturingVSAvoidvoltage tracking resistance

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent modifies the conventional flat dome surface to a curved domed surface. This curvature is integrated into the molding process, making it manufacturable while effectively increasing the track path to prevent voltage tracking in harsh environments, thus resolving the contradiction between manufacturing ease and reliability.

Inventive Principle:

Principle #14Spheroidality (Curvature)

Data Source

PatentEP3022746B1Enhanced track resistant dome structure for dry-type cast coil transformer

Publication Date: 2019.09.04 ABB (SCHWEIZ) AG

Figure 1~2
Figure 3
Figure 4A~4E

AI summary

A dry type cast coil transformer (28) includes a hollow body (29), a dome structure (26) extending from the body, and undulation structure (30), defining at least a portion of an outer surface of the dome structure, constructed and arranged to increase an electrical track path in the dome structure.