Transformer Oil Expansion Tank Airbag with Elastomer Layers

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Solution Overview

Problem

Current oil expansion tanks for transformers require frequent maintenance due to silica gel breather systems, which can lead to moisture ingress and safety risks, and existing airbags are not suitable for high-temperature applications, especially for traction transformers that operate across a wider temperature range and experience vibrations.

Innovation Solution

A flexible airbag with a sandwich structure comprising vulcanized nitrile butadiene rubber, hydrogenated nitrile butadiene rubber, or epichlorohydrin rubber elastomer layers and a reinforcement fabric layer, which provides excellent thermal ageing properties and compatibility with high-temperature oils, eliminating the need for a breather and reducing maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If silica gel breather is used to protect transformer oil from moisture, then moisture protection is improved, but maintenance frequency increases and reliability decreases

Engineering Contradiction:
Improvemoisture protectionVSAvoidsystem reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent removes the silica gel breather component from the system and replaces it with an airbag that creates a physical barrier between the transformer oil and ambient air, eliminating the need for moisture-absorbing materials that require maintenance

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The airbag system is self-maintaining as it creates a hermetic seal that passively prevents moisture ingress without requiring periodic replacement of silica gel or other active maintenance interventions

Inventive Principle:
Principle #25Self-service

2Ease of manufacture

If standard airbag materials are used for power transformers, then cost is reduced, but temperature resistance is insufficient for traction transformers

Engineering Contradiction:
Improvemanufacturing costVSAvoidtemperature resistance
Core Design Contradiction:
Ease of manufactureVSTemperature

Solution Approach 1:

The patent employs composite material construction with multiple elastomer layers (including heat-resistant materials like fluorosilicone rubber and hydrogenated nitrile butadiene rubber) combined with reinforcement layers to achieve both high-temperature resistance and cost-effectiveness

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the material composition parameters by selecting elastomers with specific glass transition temperatures and thermal stability characteristics that enable operation in the expanded temperature range of -40°C to 170°C

Inventive Principle:
Principle #35Parameter changes

3Ease of repair

If airbag is used to eliminate breather, then maintenance is reduced, but material compatibility with high-temperature oil is compromised

Engineering Contradiction:
Improvemaintenance reductionVSAvoidoil compatibility
Core Design Contradiction:
Ease of repairVSObject-affected harmful factors

Solution Approach 1:

The patent uses composite material construction with multiple elastomer layers (including heat-resistant materials like fluorosilicone rubber and hydrogenated nitrile butadiene rubber) combined with reinforcement layers to achieve both high-temperature resistance and cost-effectiveness

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent modifies the material composition parameters by selecting elastomers with specific glass transition temperatures and thermal stability characteristics that enable operation in the expanded temperature range of -40°C to 170°C

Inventive Principle:
Principle #35Parameter changes

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 flexible airbag effectively isolates transformer oil from humidity, maintains oxidation stability, and withstands temperature fluctuations from -40°C to 170°C, enhancing the reliability and reducing maintenance needs for traction transformers.

Implementation Method 1

a first and a second elastomer layer, and a reinforcement layer comprising a fabric, the reinforcement layer arranged between the first elastomer layer and the second elastomer layer

Methodology Applied
Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

the first and the second elastomer layers comprises each at least one elastomer selected from at least one of vulcanized nitrile butadiene rubber, vulcanized hydrogenated nitrile butadiene rubber or vulcanized epichlorohydrin rubber

Methodology Applied
Scientific EffectVulcanization:

Implementation Method 3

the flexible bag is configured to be operated at a temperature of 110°C or more

Methodology Applied
Scientific EffectThermal resistance:

Implementation Method 4

a reinforcement layer comprising a fabric, the reinforcement layer arranged between the first elastomer layer and the second elastomer layer

Methodology Applied
Scientific EffectMechanical reinforcement:

Implementation Method 5

Flexible bag, in particular an airbag, for an oil expansion tank of a transformer

Methodology Applied
Scientific EffectElasticity: Elasticity

Data Source

PatentEP4122704A1Flexible bag, in particular an airbag for an oil expansion tank of a transformer, oil expansion tank and transformer comprising the same and method for producing the flexible bag
Publication Date: 2023.01.25 HITACHI ENERGY LTD
  • EP4122704A1 patent drawingFigure 1a~1b
  • EP4122704A1 patent drawingFigure 1c
  • EP4122704A1 patent drawingFigure 2

AI summary

The present application relates to a flexible bag for an oil expansion tank of a transformer, an oil expansion tank comprising the flexible bag and a transformer comprising the oil expansion tank comprising the flexible bag. Further, the present application relates to a method for producing the flexible bag and use of the flexible bag in an oil expansion tank of a transformer. In particular, the present application relates to an flexible bag for an oil expansion tank of a transformer, comprising a first and a second elastomer layer, and a reinforcement layer comprising a fabric, the reinforcement layer arranged between the first elastomer layer and the second elastomer layer; and the first and the second elastomer layers comprising each at least one elastomer selected from at least one of vulcanized nitrile butadiene rubber, vulcanized hydrogenated nitrile butadiene rubber or vulcanized epichlorohydrin rubber.