Dual-Layer Fire-Resistant Cable Insulation for Extended Thermal Protection
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Solution Overview
Problem
Existing fire-resistant insulation systems for electrical cables do not provide adequate protection and functional integrity during high-stress fires, as the ceramic formation in current designs occurs at similar temperature ranges, leading to insufficient protection and a short duration of thermal insulation.
Innovation Solution
A dual-layer insulation system where the first layer forms ceramic at a higher temperature (>600 °C) and the second outer layer forms ceramic at a lower temperature range (200-600 °C), ensuring the conductor is insulated by the inner layer until the outer layer ceramizes, extending the protection duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If a single-layer fire-resistant insulation is used, then the cable has basic fire resistance, but the duration of thermal insulation protection is insufficient
Solution Approach 1:
The insulation is divided into two distinct layers: an inner layer with ceramic-forming additives that activate at higher temperatures and an outer layer with different composition that ceramizes at lower temperatures. This segmentation allows each layer to perform its protective function at different stages of thermal exposure, thereby extending the overall protection duration without excessive complexity.
Solution Approach 2:
The outer layer is designed to ceramize at lower temperatures before the inner layer activates, creating a preliminary protective ceramic barrier. This preliminary action of the outer layer provides initial protection while the conductor remains insulated by the inner layer, extending the total protection timeline.
2Reliability
If ceramic formation occurs at similar temperature ranges in all insulation layers, then the manufacturing process is simple, but the absolute protection of the conductor is insufficient
Solution Approach 1:
Different compositions are used in the inner and outer layers, with each layer containing ceramic-forming additives tailored to specific temperature ranges. The inner layer is optimized for high-temperature protection while the outer layer provides low-temperature ceramization, creating local quality differences that enhance overall conductor protection.
Solution Approach 2:
The insulation system uses composite materials with different thermal responses - the inner layer contains ceramic-forming additives for high-temperature stability while the outer layer has a different composition that ceramizes at lower temperatures. This composite structure provides multi-level protection against thermal damage.
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 dual-layer approach enhances absolute protection and extends the duration of thermal insulation, providing improved fire resistance and functional integrity by ensuring the conductor remains insulated throughout the fire, with the inner layer protecting until the outer layer ceramizes at a lower temperature.
Implementation Method 1
the formation of a ceramic in the first layer and in the second layer occurs at different temperatures
Data Source
Figure 1
AI summary
The invention relates to a wire for use in electric cables, having a fire-resistant insulation based on cross-linkable polymers comprising ceramic-forming additives, said insulation surrounding a conductor (10), wherein the insulation has a first layer (11) comprised of a first composition, and a second layer (12) comprised of a second composition surrounding the outside of the first layer (11), wherein the first and the second compositions are set such that a ceramic forms in the composition constituting the second outer layer (12) at a lower temperature range than that in the composition constituting the inner first layer (11).