Power Cable Accessory Assembly With Axial Fixation Against Shrinkback

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Solution Overview

Problem

Existing power cable accessories face issues with shrinkback, where the insulation pulls back from the conductor joint due to mechanical stresses, increasing the risk of electrical breakdown.

Innovation Solution

A power cable accessory assembly that includes a connector mechanically connected to the conductor, with a fastening device engaging the electrical insulation layer to prevent shrinkback. The connector has an inner surface structure that engages with the fastening device to maintain axial fixation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the insulation layer is stripped close to the conductor joint, then the connector can be mechanically connected to the conductor, but the insulation pulls back from the conductor joint due to built-in mechanical stresses (shrinkback)

Engineering Contradiction:

Improveelectrical breakdown riskVSAvoidinsulation position stability

Core Design Contradiction:

ReliabilityVSStability of the object's composition

Solution Approach 1:

The insulation layer is divided into two sections: a main section with larger diameter and an end section with smaller diameter. The fastening device is positioned at the transition zone between these sections, allowing the insulation to be segmented in a way that prevents shrinkback while maintaining electrical insulation integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A fastening device acts as an intermediary element between the insulation layer and the connector. This fastening device engages with both the insulation layer (at its end section) and the connector, preventing the insulation from pulling back while avoiding direct engagement that would compromise the insulation's mechanical properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Strength

If the fastening device engages with the XLPE insulation, then the connector is mechanically connected to the insulation, but the flanges in the insulation disengage at elevated temperatures due to low bending stiffness

Engineering Contradiction:

Improvemechanical connection strengthVSAvoidtemperature resistance

Core Design Contradiction:

StrengthVSTemperature

Solution Approach 1:

The insulation layer has different diameters at different locations: the main section has a larger diameter while the end section has a smaller diameter. This local variation in geometry creates a transition zone that provides enhanced mechanical engagement for the fastening device without requiring the entire insulation layer to have high bending stiffness.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

Instead of relying solely on the bending stiffness of the insulation flanges, the solution moves to another dimension by using a fastening device that engages with the insulation at its end section and connects to the connector. This dimensional shift from flange-based engagement to fastening-device-based engagement maintains mechanical connection strength at elevated temperatures.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Stability of the object's composition

If the connector engages with the insulation layer to prevent shrinkback, then the axial position is fixed, but the installation complexity increases

Engineering Contradiction:

Improveaxial position fixationVSAvoidassembly structure complexity

Core Design Contradiction:

Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The fastening device serves multiple functions: it engages with the insulation layer's end section, maintains the axial position of the connector, and prevents shrinkback. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The insulation layer is prepared in advance with a reduced diameter end section, creating a pre-formed engagement zone for the fastening device. This preliminary preparation of the insulation geometry simplifies the installation process, as the fastening device can be directly engaged with the pre-formed end section without requiring additional modification steps.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP4572049A1Power cable accessory assembly

Publication Date: 2025.06.18 NKT HV CABLES AB

Figure 1~2
Figure 3~4

AI summary

Power cable accessory assembly (1.1) comprising: a power cable (3) comprising: a conductor (5), and an electrical insulation layer (7.1) arranged around the conductor (5), wherein the electrical insulation layer (7.1) has a main section (7a) and an end section (7b), the end section (7b) having a smaller diameter than the main section (7a); a fastening device (11.1) engaging with the electrical insulation layer (7.1) in the end section (7b), and a connector (9.1) extending around the end section (7b) of the electrical insulation layer (7.1), the connector (9.1) being mechanically connected to the conductor (5), wherein the connector (9.1) has an inner surface provided with a structure that engages with the fastening device (11.1) to maintain an axially fixed position between the connector (9.1) and the electrical insulation layer (7.1).