Electrical Cable Cradle for Tensile Strength Stability

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Solution Overview

Problem

Electrical cables with long vertical runs face insufficient tensile strength, leading to potential slippage of tensile strength elements between insulated conductors under load, especially at operating temperatures, and existing solutions are either heavy or impractical for long runs.

Innovation Solution

The electrical cable design features stranded insulated conductors and tensile strength members around a cradle with a high tensile modulus polymeric material that retains shape and mechanical resistance, preventing slippage and maintaining structural integrity under tension.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If tensile strength elements are provided in the interstices between insulated conductors, then tensile strength is improved, but the elements slip between conductors under tensile load at operating temperatures

Engineering Contradiction:

Improvetensile strengthVSAvoidstability of tensile strength elements position

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The cable structure is segmented into distinct functional layers: a central cradle element, an intermediate layer with tensile strength elements positioned in grooves, and an outer layer of insulated conductors. This segmentation prevents slippage by providing dedicated positioning structures (grooves) that maintain the relative positions of tensile strength elements under thermal and mechanical stress.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The cradle element acts as an intermediary structure between the tensile strength elements and the insulated conductors. It provides a stable central core with grooves that mechanically retain the tensile strength elements, preventing their displacement under load and temperature variations while still allowing effective load transfer.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If inner PVC jacket and armor cover are used to provide tensile strength, then tensile strength is improved, but the cable becomes very heavy

Engineering Contradiction:

Improvetensile strengthVSAvoidcable weight

Core Design Contradiction:

StrengthVSWeight of moving object

Solution Approach 1:

The invention changes the material parameters by using a polymeric cradle material with specifically controlled tensile modulus (≥1 GPa) and Vicat softening temperature (≥125°C). This allows achieving the required mechanical strength and thermal stability without using heavy metallic armor or thick PVC jackets, thereby reducing overall cable weight while maintaining tensile performance.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The cable employs a composite structure combining polymeric cradle material with high tensile strength properties, insulated conductors, and tensile strength elements. This composite approach achieves the required tensile strength through material property optimization rather than relying on heavy protective layers, reducing cable weight while maintaining structural integrity.

Inventive Principle:

Principle #40Composite materials

3Strength

If offsets are used to split long vertical runs, then tensile strength requirements are reduced, but installation complexity and real estate consumption increase

Engineering Contradiction:

Improvetensile strength requirementVSAvoidinstallation complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The invention changes the cable's mechanical parameters by incorporating tensile strength members that increase the cable's overall tensile capacity. This allows the cable to withstand the full tension of long vertical runs without requiring offset installations, maintaining straight-run simplicity while achieving the necessary strength through modified cable construction.

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

This configuration provides enhanced tensile strength and flexibility, ensuring the cable's structural stability and load transfer without the weight and practicality issues of previous solutions, while maintaining flexibility and adhering to industry safety factors.

Implementation Method 1

the cradle is made of polymeric material having a tensile modulus greater than or equal to 1 GPa and a Vicat softening temperature greater than or equal to 125° C.

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS10109392B2Electrical cables with strength elements

Publication Date: 2018.10.23 PRYSMIAN SPA

AI summary

An electrical cable may include: at least two first members extending along a length of the electrical cable, each of the first members including a conducting element and an insulating layer radially external to the conducting element; at least two second members extending along the length of the electrical cable, each of the second members including a strength element and a conductive layer radially external to the strength element; and/or the first and second members being stranded around and in contact with a cradle extending along the length of the electrical cable. The cradle may be made of polymeric material having a tensile modulus greater than or equal to 1 GPa and a Vicat softening temperature greater than or equal to 125° C.