Step-Lap Transformer Core Structure for Corrosion-Resistant Joints

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Solution Overview

Problem

Submersible dry-type transformers are prone to corrosion due to harsh environmental exposure, which affects their electromagnetic performance, and existing laminated core constructions struggle to adequately protect the transformer core from corrosion, especially in areas with water, humidity, and pollution.

Innovation Solution

A step-lap sequence laminated core construction method where laminations of varying lengths are stacked to form joints with enlarged valleys, allowing for better application and protection by anti-corrosive coatings, reducing manufacturing complexity and improving magnetic flux flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional laminated core construction is used, then manufacturing is simpler, but corrosion resistance is insufficient in harsh environments

Engineering Contradiction:
Improvecorrosion resistanceVSAvoidlaminated core construction complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The core is divided into multiple laminations with varying lengths arranged in a step-lap sequence, creating segmented joints with enlarged valleys. This segmentation allows anti-corrosive coatings to be effectively applied and retained in the joint areas, significantly improving corrosion resistance while maintaining manageable construction complexity through systematic arrangement of the segmented parts.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The step-lap sequence creates local variations in lamination lengths, producing enlarged valleys at specific joint locations. These localized structural modifications concentrate corrosion protection efforts where they are most needed (at the joints), while the rest of the core maintains its standard construction, thus improving overall corrosion resistance without uniformly increasing complexity throughout the entire core structure.

Inventive Principle:
Principle #3Local quality

2Reliability

If laminations are stacked with varying lengths to form step-lap joints, then corrosion protection is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveanti-corrosion performanceVSAvoidlaminated core assembly ease
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The laminations are pre-configured with varying lengths and arranged in a predetermined step-lap sequence before assembly. This preliminary preparation of the lamination dimensions and arrangement pattern simplifies the actual assembly process, as the components are designed to fit together systematically rather than requiring complex adjustments during assembly, thus improving anti-corrosion performance while maintaining ease of manufacture.

Inventive Principle:
Principle #10Preliminary action

3Loss of energy

If at least four identical laminations are stacked directly to each other in the step-lap sequence, then magnetic flux flow is improved, but the number of laminations increases

Engineering Contradiction:
Improvemagnetic flux efficiencyVSAvoidnumber of laminations
Core Design Contradiction:
Loss of energyVSQuantity of substance

Solution Approach 1:

Four or more identical laminations are stacked directly to each other in sequence, merging their magnetic paths to create continuous, unbroken magnetic flux flow channels. This merging reduces magnetic flux losses by eliminating air gaps and discontinuities that would otherwise occur at joint locations, thereby improving magnetic flux efficiency. The systematic stacking pattern allows this benefit to be achieved with a manageable increase in lamination quantity through efficient space utilization.

Inventive Principle:
Principle #5Merging (Combining)

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

Enhances corrosive resistance, reduces transformer noise, and improves overall performance by ensuring effective protection of the transformer core from harsh environments and maintaining magnetic flux efficiency.

Implementation Method 1

improving magnetic flux flow

Methodology Applied
Scientific EffectMagnetic flux flow: Magnetic Field

Implementation Method 2

laminated core construction

Methodology Applied
Scientific EffectEddy current reduction: Eddy Currents

Data Source

PatentEP3769324B1Transformer cores and assembly methods thereof for high efficiency and high Anti-corrosion performance
Publication Date: 2023.08.30 SIEMENS ENERGY GLOBAL GMBH & CO KG
  • EP3769324B1 patent drawingFigure 1
  • EP3769324B1 patent drawingFigure 2~3
  • EP3769324B1 patent drawingFigure 4~8

AI summary

A transformer core for a dry-type transformer includes a laminated construction having several groups of stacked laminations that form a step-lap sequence of laminations. Each group in the step-lap sequence has a mean length different than an adjacent group in the step-lap sequence and has at least two identical laminations per group, wherein at least one group has at least four identical laminations. Methods of assembling a transformer core are also provided, as are other aspects.