Cable Grip Managing Thermal Expansion on Ladder Rungs

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Solution Overview

Problem

Cables secured to ladder rungs experience damage due to unmanaged thermal expansion and contraction, leading to displacement and disconnection from termination points, particularly in vertical applications where expansion and contraction cause length differences and weight-induced contraction issues.

Innovation Solution

A cable securing sub-system comprising a cable grip with a protective grommet, metal plate, and wire forms to secure cables to a ladder rung, along with a cable divider and containment clamp, allowing for vertical movement and managing thermal expansion and contraction by creating a natural bend point and maintaining cable separation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If cables are secured rigidly to ladder rungs, then cable stability and secure attachment are improved, but thermal expansion and contraction cause cable damage and displacement

Engineering Contradiction:
Improvecable secure attachmentVSAvoidthermal expansion damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The cable securing system transitions from a rigid fixed position to a dynamic configuration that permits controlled movement. The cable grip allows the cable to move vertically along the ladder rung while maintaining lateral securement, enabling the system to adapt to thermal expansion and contraction forces without causing damage or displacement.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The cable support function is divided into two independent components: lateral securing (performed by the cable grip attached to the ladder rung) and vertical positioning (allowed to move freely). This segmentation enables each component to perform its specific function optimally - the grip provides stable attachment while the cable maintains vertical mobility to accommodate thermal changes.

Inventive Principle:
Principle #1Segmentation

2Object-affected harmful factors

If cables are allowed to move freely during thermal expansion, then cable damage is prevented, but cable stability and secure attachment deteriorate

Engineering Contradiction:
Improvecable damage preventionVSAvoidcable secure attachment
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The cable grip applies different constraints to different directions of cable movement. It provides rigid lateral constraint to prevent horizontal displacement and maintain secure attachment, while allowing vertical movement to accommodate thermal expansion and contraction. This directional differentiation of constraint quality resolves the contradiction between stability and damage prevention.

Inventive Principle:
Principle #3Local quality

3Area of stationary object

If multiple cables are secured close together on ladder rungs, then space utilization is improved, but thermal expansion causes cable interference and damage

Engineering Contradiction:
Improveladder rung space utilizationVSAvoidcable interference during expansion
Core Design Contradiction:
Area of stationary objectVSObject-affected harmful factors

Solution Approach 1:

The solution addresses cable expansion interference by utilizing the vertical dimension rather than increasing horizontal spacing. The cable grip secures cables laterally in close proximity to maximize space utilization, while the vertical movement capability allows each cable to expand and contract independently without interfering with adjacent cables.

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

4Ease of manufacture

If cables are secured at the top of the ladder rung, then installation simplicity is improved, but weight-induced contraction causes cables to pull out of lugs

Engineering Contradiction:
Improveinstallation simplicityVSAvoidcable termination stability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The cable grip provides a dynamic attachment point that moves with the cable during thermal contraction. Instead of a fixed termination at the top of the ladder rung that is vulnerable to pull-out forces, the grip allows the cable to move vertically while maintaining secure lateral attachment, preventing termination failure during contraction cycles.

Inventive Principle:
Principle #15Dynamics

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 system effectively prevents cable damage by allowing controlled movement during thermal expansion and contraction, ensuring secure attachment and maintaining cable integrity and voltage rating, while simplifying installation and ensuring consistent spacing across ladder rungs.

Implementation Method 1

The normal operation of electrical equipment causes the temperature of conductors to fluctuate in a wide range. The change in temperature of the conductors will cause the conductors to expand and/or contract.

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

The contraction of the cables is even worse because the weight of the cables makes it easier for the cables to contract at the top of the cable.

Methodology Applied
Scientific EffectThermal contraction: Thermal Contraction

Implementation Method 3

The thermal expansion becomes even more difficult to manage in a vertical application. When the cables expand the difference in length must be managed or damage will occur.

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Data Source

PatentEP3149820B1A cable securing subsystem for securing cables to a ladder rung
Publication Date: 2020.02.19 PANDUIT CORP
  • EP3149820B1 patent drawingFigure 1
  • EP3149820B1 patent drawingFigure 2~3
  • EP3149820B1 patent drawingFigure 4

AI summary

The present invention is directed to a thermal expansion and contraction system for securing cables to a ladder rung. The thermal expansion and contraction system includes a cable grip secured to the ladder rung. The cable grip includes a protective grommet for holding cables to the ladder rung, a metal plate and wire forms to secure the protective grommet to the metal plate. The thermal expansion and contraction system also includes a cable divider secured to the ladder rung to maintaining separation of cables and a cable containment clamp secured to the ladder rung.