| FEP: Features and Properties
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Extruded FEP insulated high voltage wire and cable offers exceptional dielectric strength without the disadvantages common to equally rated silicone rubber insulated cables. As a result, cable assemblies or cable bundles are of smaller diameter and therefore take up substantially less volume and have a smaller bend radius which allows the designer to better utilize the space within the system. It has good corona inception qualities and its construction gives it excellent durability and resistance to dielectric/cooling fluid degradation.
While difficult to bond to, with the use of Reynolds proper abrading and coating preparations an excellent silastic bond is possible. Additionally, FEP insulation, being a harder material than silicone rubber, is not prone to pin-holing and high voltage punch-thru when the cable surface is abraded or when strands break during in-field service. FEP is also more resistant to damage when making contact with sharp edges.
FEP cable should not only be considered for use in cable assemblies, but as high voltage hook-up wire within encapsulated high voltage power supplies, TWTs and transformers.
Low DC corona inception, particularly after numerous temperature cycles, is another advantage of FEP over silicone cables. Teflon tape wrapped cable, which is similar to FEP in dielectric strength and corona inception, is difficult to bond to because of its multiple spiral cross section, irregular surface and variations in diameter
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| Properties of FEP Fluorocarbon Resin |
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| Physical, Thermal and Electrical Properties |
Typical Values
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| Specific Gravity |
2.14
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| Tensile Strength (PSI) |
3,500
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| Elongation (%) |
325
|
| Flexual Modules (PSI) |
90,000
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| Thermal Conductivity (cal/sec/cm°F) |
6X10
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| Continuous Use Temperature (°C) |
204
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| Melt Temperature (°C) |
255–265
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| Low Temperature Limit (°C) |
-240
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| Hardness Durometer |
D56
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| Water Absorption (%) |
<01
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| Flame Resistance |
Excellent
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| Dielectric Constant, 60-10 Hz |
2.1
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| Dissipation Factor, 60-10 Hz |
<.0007
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| Volume Resistivity (Ohms-Cm) |
<10
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| Surface Resistivity (Ohms/Sq.) |
<10
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| Resistance to: |
Rating
|
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| Cold Flow or Cut Through |
Fair
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| Ultraviolet Radiation |
Excellent
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| Electro-Mechanical Stress Cracking |
Excellent
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| Chemical-Mechanical Stress Cracking |
Excellent
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Conductor Material
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| Copper |
Conductor Finish
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Silver Plate- per test requirements of ASTM B298. Meets solderability per MIL-STD-202.
Note: Pre-conditioning of FEP cable after cutting to length is recommended because FEP cable will shrink when exposed to temperature cycling. Pre-conditioning should be conducted in an air circulating oven at 204°C (400°F) for one hour. |
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