A CABLE SYSTEM must withstand any environment in which it will be used. Many applications in harsh environments demand that cable systems perform beyond conventional safety, environmental, and performance-related standards. Examples include aerospace, cleanroom, and geophysical environments. In an 11-page white paper titled "Selecting the Right Cable System for Your Environment," W.L. Gore & Associates' Lead Design Engineer, Paul Warren, offers a systematic approach that will help design engineers ensure that a cable system will provide reliable performance in both demanding environments and mission-critical applications.
Regardless of the target application, Warren emphasizes that it is possible to identify all of the factors that may affect the electrical performance of a cable system. To follow the suggested approach, one should first list the constraints that will affect performance including electrical, mechanical, environmental, and application-specific factors. This list should then be shared with cable manufacturers so that they can select the optimal materials and construction. Through data testing and analysis, the manufacturer also should demonstrate that the cable will meet its rated performance specifications in a given environment.
The paper identifies potential constraints and defines them. For example, signal integrity may be compromised by electromagnetic interference (EMI), crosstalk, attenuation, and conductor resistance. Mechanical, environmental, and application-specific stress factors also are detailed. The document then reviews the design of the cable system itself.
Given that the material chosen for cable insulation and jacketing is critical, the author provides insight into many commonly used options. Silicone, for instance, is flexible and offers benefits like superior dielectric strength and high-voltage conductor insulation. Yet it cuts easily. In addition, its sticky surface results in a high coefficient of friction. Both advantages and disadvantages also are provided for polyurethane, polyethylene, and fluoropolymers and enhanced fluoropolymers.
Finally, be sure to find out what level of performance testing has been done to ensure that the cable will perform reliably in the target application. Mechanical testing also should be done to verify the electrical performance of the cable while it is working in the conditions of the end application. Environmental conditions should be simulated as well. Before selecting a cable system, an engineer should perform a cost analysis that considers the full system-level impact of a cable failure.
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