Dry Transformer Cooling with Wall-like Diaphragms

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Solution Overview

Problem

Dry transformers face challenges in achieving homogeneous temperature distribution due to heat radiation between coils, leading to inhomogeneous temperature distribution and potential insulation loss, especially in polygonal or triangular arrangements where the axial center area experiences higher temperatures.

Innovation Solution

A cooling system with wall-like diaphragms between coils, oriented parallel to the transformer limbs, forming a star-like arrangement and acting as guide plates for natural airflow, with a chimney around the virtual center axis to enhance cooling, and optionally using heat-absorbing materials and heat pipes for improved heat transfer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If transformer coils are arranged in a polygonal or triangular manner to increase power density, then the transformer can handle higher power levels, but the axial center area experiences increased heat radiation and higher temperatures leading to inhomogeneous temperature distribution

Engineering Contradiction:
Improvepower densityVSAvoidtemperature distribution homogeneity
Core Design Contradiction:
PowerVSTemperature

Solution Approach 1:

The patent introduces a cooling module with a chimney structure as an intermediary element in the axial center area. This chimney acts as a mediator that facilitates natural convection cooling by creating an upward airflow path, thereby reducing the temperature in the axial center region where heat radiation from multiple coils converges. The cooling module serves as a buffer between the heat-generating coils and the surrounding environment, improving temperature distribution homogeneity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent modifies the thermal parameters in the axial center area by introducing a chimney structure that changes the convection pattern. The chimney creates a localized upward airflow that enhances heat removal from the axial center region, thereby changing the temperature distribution parameter from inhomogeneous to more uniform across the transformer coils.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If cooling channels are integrated into transformer coils to improve cooling efficiency, then temperature distribution improves, but the device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improvecooling efficiencyVSAvoidstructural complexity
Core Design Contradiction:
TemperatureVSDevice complexity

Solution Approach 1:

Instead of integrating cooling channels directly into each coil (which would increase complexity), the patent segments the cooling function into a separate, modular cooling module with a chimney structure. This segmentation allows the cooling system to be added as a distinct component that addresses the thermal issue without complicating the coil design and manufacturing process.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The cooling module with chimney serves as an intermediary cooling system that operates independently from the coil structure. It provides effective cooling through natural convection without requiring integration with the coil windings, thereby maintaining simplicity in coil manufacturing while achieving improved temperature distribution.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Temperature

If additional cooling components are added to reduce temperature in the axial center area, then temperature distribution homogeneity improves, but the transformer volume and space requirements increase

Engineering Contradiction:
Improvetemperature distribution homogeneityVSAvoidtransformer volume
Core Design Contradiction:
TemperatureVSVolume of stationary object

Solution Approach 1:

The chimney structure in the axial center area serves multiple functions: it acts as a cooling channel for natural convection, provides structural support in the center region, and facilitates airflow path organization. This multi-functionality allows effective cooling to be achieved without proportionally increasing the transformer volume, as the chimney utilizes existing spatial configuration.

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

Solution Approach 2:

The patent addresses the temperature issue in the axial center area by introducing a vertical chimney structure that utilizes the vertical dimension for natural convection cooling. This dimensional approach allows heat removal without requiring additional horizontal space, thereby maintaining compact transformer volume while improving temperature distribution.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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

The solution effectively reduces temperature within the axial center area, achieving a more homogeneous temperature distribution across the transformer coils while minimizing additional space requirements and simplifying assembly and maintenance.

Implementation Method 1

forming a star-like arrangement and acting as guide plates for natural airflow

Methodology Applied
Scientific EffectNatural convection: Free Convection

Implementation Method 2

optionally using heat-absorbing materials and heat pipes for improved heat transfer

Methodology Applied
Scientific EffectHeat radiation absorption: Absorption (EM radiation)

Implementation Method 3

optionally using heat-absorbing materials and heat pipes for improved heat transfer

Methodology Applied
Scientific EffectHeat pipe effect: Heat Pipe

Data Source

PatentEP2490231B1Cooling system for dry transformers
Publication Date: 2014.11.26 ABB TECHNOLOGY AG
  • EP2490231B1 patent drawingFigure 1~2
  • EP2490231B1 patent drawingFigure 3~4

AI summary

The invention is related to a dry transformer (40), comprising a transformer core (10) with at least two parallel limbs (12, 14, 16, 58, 60, 62) and belonging upper (26, 28, 30, 42, 44, 46) and lower (20, 22, 24) yokes and at least two hollow cylindrical coils (32, 52, 54, 56, 112, 114), each arranged around a limb (12, 14, 16, 58, 60, 62). A cooling system comprising at least one wall-like diaphragm (74, 90, 102) in-between neighboured coils (52, 54, 56; 112, 114) is foreseen which is in parallel to the orientation of the limbs (12, 14, 16, 58, 60, 62).