Monolithic Coil Fixture for Oil Transformer Axial Strength

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Solution Overview

Problem

Conventional coil fixtures for high voltage transformers require significant space for axial strengthening, which reduces the theoretical maximum rated power due to the need for separate press rings and spacer rings, leading to inefficient use of transformer size.

Innovation Solution

A monolithic coil fixture with rib-like spacer elements arranged to enhance flexural strength, manufactured as a single part using milling techniques, reduces height while maintaining mechanical stiffness and allowing for improved oil flow and insulation, thereby optimizing space usage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If separate press rings and spacer rings are used for axial strengthening, then mechanical strength is improved, but device complexity and space consumption increase

Engineering Contradiction:
Improveaxial mechanical strengthVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The patent combines the press ring and spacer ring into a single integrated coil fixture that performs both mechanical strengthening and insulation functions simultaneously. This monolithic structure eliminates the need for separate components while maintaining axial strength against short-circuit forces.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The integrated coil fixture serves multiple functions: it provides axial mechanical support against short-circuit forces, acts as an electrical insulator between the coil and core, and maintains proper spacing. This multi-functional design reduces overall device complexity while achieving all required performance targets.

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

2Strength

If separate press rings and spacer rings are used for axial strengthening, then mechanical strength is improved, but the axial length increases reducing rated power

Engineering Contradiction:
Improveaxial mechanical strengthVSAvoidaxial length
Core Design Contradiction:
StrengthVSLength of moving object

Solution Approach 1:

By merging the press ring and spacer ring into one integrated component, the patent eliminates the cumulative axial length of two separate rings. The single fixture achieves the same mechanical strengthening effect while occupying less axial space, thereby increasing the available length for windings and rated power.

Inventive Principle:
Principle #5Merging (Combining)

3Strength

If conventional press ring and spacer ring arrangement is used, then axial strengthening is achieved, but space utilization is reduced

Engineering Contradiction:
Improveaxial mechanical strengthVSAvoidspace utilization
Core Design Contradiction:
StrengthVSVolume of moving object

Solution Approach 1:

The integration of multiple functions into a single coil fixture reduces the total volume occupied by supporting structures. This freed-up space can be utilized for additional windings or other electrically active parts, thereby increasing the transformer's rated power within the same physical envelope.

Inventive Principle:
Principle #5Merging (Combining)

4Volume of moving object

If monolithic coil fixture is used, then space is reduced and rated power is improved, but manufacturing complexity increases

Engineering Contradiction:
Improveaxial lengthVSAvoidmanufacturing complexity
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent employs modern manufacturing techniques such as milling and laminated material construction to produce the monolithic fixture. These methods, while requiring specialized equipment, enable the creation of complex integrated geometries that would be difficult to assemble from separate parts, ultimately simplifying the overall structure.

Inventive Principle:
Principle #35Parameter changes

5Strength

If rib-like spacer elements are integrated into monolithic structure, then flexural strength is improved, but manufacturing difficulty increases

Engineering Contradiction:
Improveflexural strengthVSAvoidmanufacturing difficulty
Core Design Contradiction:
StrengthVSEase of manufacture

Solution Approach 1:

The rib-like spacer elements are integrated into the monolithic structure using milling techniques and laminated materials. These manufacturing approaches allow for the creation of optimized rib geometries that maximize flexural strength while being produced as a single integrated component, eliminating assembly complexity.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP2602799B1Coil-fixture and oil-transformer
Publication Date: 2015.12.02 ABB (SCHWEIZ) AG
  • EP2602799B1 patent drawingFigure 1~2
  • EP2602799B1 patent drawingFigure 3~4
  • EP2602799B1 patent drawingFigure 5~6

AI summary

The invention is related to a coil-fixture (10, 36, 38, 60, 62, 70, 90) for mounting on a front side of a hollow cylindrical high voltage transformer coil (32, 58), comprising a ring-shaped ground plate (12, 72, 164) with an inner opening (14, 80, 114) for a limb (54, 56) of a transformer core (52) and rib-like spacer-elements (16, 18, 74, 76, 92, 94, 96, 98) suitable for supporting at least the weight of a belonging transformer coil (32, 58), which are arranged flat on one side of the ground-plate (12, 72, 164). Flow-channels (24, 26, 40, 42, 108, 110, 112) are foreseen inbetween the spacer elements (16, 18, 74, 76, 92, 94, 96, 98), which are leading directly or indirectly to an area around the inner opening (14, 80, 114). The ground-plate (12, 72, 164) and the rib-like spacer elements (16, 18, 74, 76, 92, 94, 96, 98) are manufactured as one monolithic part.. The invention also relates to an oil transformer, comprising a transformer vessel and a transformer core (52) with at least one transformer coil (32, 58) mounted therein, whereas the transformer coil is clamped inbetween two coil fixtures (10, 36, 38, 60, 62, 70, 90) whereas at least one coil fixture is built according to the invention.