Cable Termination Pressure Relief via Segmented Ring Opening

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Solution Overview

Problem

Existing cable terminations with insulating fluid fillings, such as silicone oils, are prone to destruction and uncontrolled part detachment during internal arc accidents due to insufficient pressure relief, leading to environmental damage and safety hazards from flying debris.

Innovation Solution

A cable termination design featuring large-area pressure relief openings, secured by closure and securing means, including ring-segment-shaped openings and a bursting disk, to manage internal pressure without allowing uncontrolled part detachment, utilizing a rotationally symmetrical glass fiber reinforced plastic insulating housing with metal rings and sealing mechanisms to contain the insulating fluid.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If small-area pressure relief openings are used in cable terminations filled with insulating fluid, then the structural integrity is maintained under normal conditions, but the pressure relief capability is insufficient during arcing accidents leading to destruction and uncontrolled part detachment

Engineering Contradiction:
Improvepressure relief capabilityVSAvoidstructural integrity
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The pressure relief opening is designed as a ring-segment shape divided into multiple segments by webs, allowing the opening to be segmented into controlled sections. This segmentation enables the opening to relieve pressure effectively while maintaining structural integrity through the connecting webs that prevent uncontrolled part detachment.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The closure means is designed to transition from a closed state during normal operation to an opened state when predeterminable internal pressure is exceeded. This dynamic behavior allows the system to maintain structural integrity under normal conditions while providing adequate pressure relief capability during arcing accidents.

Inventive Principle:
Principle #15Dynamics

2Reliability

If large-area pressure relief openings are designed to relieve explosive pressure, then the pressure relief capability is improved, but parts may become detached and fly away uncontrolled

Engineering Contradiction:
Improvepressure relief capabilityVSAvoiduncontrolled part detachment
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The ring-segment-shaped opening is divided into multiple segments by webs that connect the opening sections. This segmentation allows large-area pressure relief while the webs prevent complete detachment of parts, ensuring that even under explosive pressure conditions, parts cannot fly away uncontrolled.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The webs act as intermediary elements between the pressure relief function and the structural integrity requirement. These webs allow pressure to escape through the ring-segment opening while simultaneously serving as retaining structures that prevent uncontrolled part detachment during arcing accidents.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Strength

If the cable termination is designed with a self-supporting structure, then the mechanical stability is improved, but the complexity of securing means increases

Engineering Contradiction:
Improvemechanical stabilityVSAvoidsecuring means complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The closure means and securing means are merged into a single integrated component system. The closure means serves both to seal the pressure relief opening during normal operation and to act as securing means that prevents uncontrolled part detachment when pressure exceeds predeterminable levels, thereby reducing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The closure means is designed with multi-functionality, serving as both a sealing element during normal operation and as a securing element during pressure relief events. This universal design eliminates the need for separate securing means, reducing device complexity while maintaining mechanical stability.

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

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

Prevents destruction and uncontrolled part detachment during arcing accidents by allowing controlled pressure relief, ensuring the safety of people and the environment by maintaining structural integrity and containing the insulation medium.

Implementation Method 1

closure means allowing the at least one pressure relief opening to be opened when a predeterminable internal pressure is exceeded

Methodology Applied
Scientific EffectPressure relief: Pressure Increase

Implementation Method 2

The ring is secured with shear bolts that must have a specified tensile strength

Methodology Applied
Scientific EffectShear strength: Shear Stress

Implementation Method 3

an insulating housing for accommodating a fluid insulating medium, preferably insulating oil

Methodology Applied
Scientific EffectElectrical insulation: Dielectric

Data Source

PatentEP2259401B1Cable end closure for open air or indoor use
Publication Date: 2012.09.26 NKT GMBH & CO KG
  • EP2259401B1 patent drawingFigure 1
  • EP2259401B1 patent drawingFigure 2~3

AI summary

The closure (10) has lockable pressure discharge openings (36.1, 58) formed for an insulation medium, which forms an opening during exceedance of predetermined inner pressure. The pressure discharge openings are formed in a plate (52) in a bottom fitting (50) and/or in a plate (32) in a top fitting (30). The two plates are extensively penetrated by the pressure discharge openings. Closure units closing the pressure discharge openings are formed such that parts of the closure are not detached during exceedance of the inner pressure in an uncontrolled manner.