Fire Rated Coaxial Cable Ceramic Dielectric Design
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Solution Overview
Problem
Conventional coaxial cables fail to meet fire code standards due to dielectric materials melting at high temperatures, leading to short circuits and signal attenuation, and existing solutions are either non-manufacturable or too rigid.
Innovation Solution
A coaxial cable design incorporating a fire retardant outer protective structure, such as fire retardant tape or stainless steel, to prevent oxidation and maintain conductor separation, combined with a high-temperature resistant dielectric, like ceramic beads in a flame retardant tape, to ensure functionality during fires and extreme temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional dielectric materials are used in coaxial cables, then the cable is flexible and easy to install at normal temperatures, but the dielectric melts at high temperatures (around 148.9°C) causing short circuits and failure during fires
Solution Approach 1:
The patent changes the material parameter of the dielectric from conventional plastic (melting point ~148.9°C) to ceramic beads (melting point >1000°C), fundamentally altering the temperature resistance parameter to withstand fire conditions while maintaining electrical insulation properties
Solution Approach 2:
The patent creates a composite dielectric structure by embedding ceramic beads within a fire retardant tape matrix, combining the high temperature resistance of ceramic with the structural support and flexibility of the fire retardant material to achieve both thermal stability and mechanical performance
2Temperature
If copper conductors are used in coaxial cables, then the cable provides good electrical conductivity, but the copper oxidizes at high temperatures forming cupric oxide that makes the conductor brittle and prone to breaking
Solution Approach 1:
The patent creates an inert protective environment by wrapping the copper conductors in fire retardant tape and fire retardant construction material that prevents oxygen access, thereby eliminating the oxidation reaction that would otherwise occur at high temperatures and cause conductor brittleness
Solution Approach 2:
The patent applies fire retardant tape and construction material as protective barriers before exposure to fire, cushioning the copper conductors against oxidative damage by preventing direct contact between oxygen and the conductor surface during high temperature events
3Temperature
If fire retardant materials are used to protect the cable, then the cable can withstand high temperatures, but the cable becomes too rigid for practical installation
Solution Approach 1:
The patent uses fire retardant tape wrapped around the cable components and fire retardant construction material as flexible protective layers that provide thermal protection while maintaining sufficient flexibility for cable installation, avoiding the rigidity problems of solid fireproof enclosures
Solution Approach 2:
The patent segments the fire protection into multiple thin layers (fire retardant tape, fire retardant construction material) rather than using a single thick rigid barrier, allowing the cable to maintain flexibility while achieving adequate fire resistance through cumulative protection
4Reliability
If the cable is designed to meet fire code standards, then the cable can survive 2-hour burn tests, but existing cables either burn or deform causing inner conductor to short circuit with outer conductor
Solution Approach 1:
The patent employs composite materials including fire retardant tape, fire retardant construction material, and ceramic bead dielectric that collectively provide both fire code compliance (surviving 2-hour burn tests) and mechanical strength to maintain conductor separation under extreme thermal stress
Solution Approach 2:
The patent pre-applies multiple layers of fire retardant tape and construction material as protective barriers before fire exposure, cushioning the cable structure against thermal deformation and preventing the conductor separation failures that occur in conventional cables during burn tests
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 cable effectively withstands high temperatures, prevents conductor oxidation, and maintains signal integrity, passing rigorous fire and functionality tests, including the 2-hour burn test and water hose blast test, while being flexible enough for installation.
Implementation Method 1
an outer protective structure or barrier to seal the coaxial cable assembly from air and protect the outer and inner conductors from oxidation in a fire
Implementation Method 2
a high-temperature resistant dielectric, like ceramic beads in a flame retardant tape, to ensure functionality during fires and extreme temperatures
Data Source
Figure 1
Figure 2~2(c)
Figure 3~4
AI summary
A coaxial cable (10) is provided that includes an outer barrier (12, 14, 16) that seals the coaxial cable (10)from air and protects the cable's conductors (18, 20) from oxidation in a fire. Such an outer protective barrier (12, 14, 16) may include a fire retardant tape. A dielectric (22) separates the conductors (18, 20)and may comprise a ceramic (23) embedded in a dielectric material (25), or ceramic beads (110, 53)in a braided ceramic mesh(120, 55).