Transformer Core Stray Field Shield Integration

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Solution Overview

Problem

Existing transformer cores experience significant magnetic losses due to leakage flux, leading to unwanted heating and reduced reliability, particularly in oil-filled transformers, and current shielding solutions require additional space and complex production processes.

Innovation Solution

Integrating a laminated stray field shield with layer planes perpendicular to the core limb laminations, which serves as both a shield for leakage flux and carries part of the main flux, eliminating the need for separate shielding elements and reducing eddy currents by using the outer core stage for dual functionality.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a separate magnetic shield is added to shield leakage flux, then magnetic losses are reduced, but device complexity and installation space increase

Engineering Contradiction:
Improvemagnetic lossesVSAvoidshielding structure complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent combines the stray field shield with the end lamina of the core limb, making them a single integrated component. The end lamina itself is configured to serve as the shield, eliminating the need for separate shielding elements and their associated fastening devices. This merging reduces structural complexity while maintaining the shielding function against leakage flux.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The end lamina performs multiple functions simultaneously: it closes the laminated core structurally and acts as a stray field shield against leakage flux. By making the end lamina itself the shielding element, the design achieves multi-functionality without adding extra components, thereby reducing both complexity and installation space requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Loss of energy

If a magnetic shield with clamping devices is used, then leakage flux shielding is improved, but the winding window space is reduced

Engineering Contradiction:
Improveleakage flux shieldingVSAvoidwinding window space
Core Design Contradiction:
Loss of energyVSVolume of stationary object

Solution Approach 1:

The shield is merged with the end lamina, eliminating separate clamping devices and their associated space requirements. The integrated design uses the end lamina's own structure to provide shielding, removing the need for additional fastening elements that would occupy valuable winding window space.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The patent extracts and eliminates the clamping devices from the design by making the end lamina itself the shielding element. This removal of unnecessary components frees up winding window space for the electrical winding while maintaining effective leakage flux shielding through the integrated end lamina configuration.

Inventive Principle:
Principle #2Taking out (Extraction)

3Stability of the object's composition

If massive carrier plates and clamping wedges are used to secure the shield, then shielding stability is improved, but production complexity and cost increase

Engineering Contradiction:
Improveshield stabilityVSAvoidproduction complexity
Core Design Contradiction:
Stability of the object's compositionVSEase of manufacture

Solution Approach 1:

The end lamina and shield are merged into a single component, eliminating the need for carrier plates, clamping wedges, and other fastening devices. This integration simplifies the manufacturing process by reducing the number of parts that need to be produced and assembled, while the end lamina's inherent structural design provides sufficient stability.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The lamination structure itself provides segmentation and stability without requiring additional fastening components. Each lamination layer contributes to the overall structural integrity and shielding effectiveness, allowing the design to achieve stability through the layered construction rather than through massive carrier plates and clamping mechanisms.

Inventive Principle:
Principle #1Segmentation

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 design significantly reduces magnetic losses, minimizes 'hot spots', maintains a compact structure, and lowers production costs by eliminating the need for additional space and complex fastening devices, thereby enhancing the technical reliability of transformers.

Implementation Method 1

eddy current losses that are induced by the change in a magnetic flux over time can be kept low

Methodology Applied
Scientific EffectEddy currents: Eddy Currents

Implementation Method 2

field lines of the leakage flux that penetrate into a broad surface of an end lamina of a core limb laminated core cause magnetic losses there through induction

Methodology Applied
Scientific EffectMagnetic flux: Magnetic Field

Data Source

PatentEP2206126B1Transformer core having a stray field shield
Publication Date: 2012.03.14 SIEMENS TRANSFORMERS AUSTRIA
  • EP2206126B1 patent drawingFigure 1
  • EP2206126B1 patent drawingFigure 2
  • EP2206126B1 patent drawingFigure 3

AI summary

The invention relates to a transformer core having a stray field shield, comprising at least one core leg (2', 2'', 2''') carrying a winding arrangement (13) and formed from a laminate stack (3), said laminate stack (3) being sealed by end plates (7', 7''), each end plate (7', 7'') being associated with a stray field shield (4', 4'') that comprises coated laminate plates (40', 40''), the layer planes (15) of which are disposed perpendicular to the layer planes (14) of the laminate stack (3), characterized in that the laminate plates (40', 40'') are disposed with laminate plate faces (9', 9'') pointing toward the laminate stack (3) to abut an exterior width surface (8', 8'') of an associated end plate (7', 7'').