SIST EN 4674-004:2018

Overview

SIST EN 4674-004:2018 is a European Standard within the Aerospace series that specifies requirements for self-wrapping shielding (EMI) protective sleeves used in electrical cable installations outside pressurized areas. These open sleeves provide electromagnetic interference (EMI) protection up to 10 kA and operate within a temperature range of -65 °C to 200 °C. Constructed from nickel-plated copper strands and polyphenylene sulphide (PPS) monofilament, these flexible EMI sleeves are designed to safeguard electrical cables and cable bundles in aerospace applications.

Developed by the Aerospace and Defence Industries Association of Europe (ASD-STAN) and approved by CEN, this standard is harmonized across many European countries and aligns with other aerospace testing and material standards. It supersedes EN 4674-004:2015, ensuring updated performance and testing criteria are met.

Key Topics

• Material Composition: The EMI protective sleeve combines nickel-plated copper wire with PPS monofilaments for flexibility and durability. An optional internal mechanical protection tape compliant with ASTM D4894 can be included for electrical insulation between cables and the metallic braid.

• Dimensions and Sizes: Sleeves come in multiple size codes ranging from 0-5 mm to 38-45 mm diameters. Specifications include wall thickness and mass per meter, both for sleeves with and without internal protective tape.

• Electrical Characteristics:

  • The sleeve provides EMI protection rated up to 10 kA.
  • Maximum allowable DC electrical resistance is defined per size to maintain shielding effectiveness after endurance tests.
  • Transfer impedance, a critical parameter for EMI suppression, must remain below specified limits across a frequency range, verified by triaxial test methods.

• Thermal Range: Engineered to operate reliably between -65 °C and 200 °C, ensuring performance even in extreme environmental conditions commonly encountered in aerospace applications.

• Test Methods: Comprehensive test regimes cover visual inspection, dimensional analysis, tensile strength retention under high temperature and fluid exposure, flammability, vibration endurance, dynamic cut-through resistance, and transfer impedance. Additional tests include salt mist exposure for corrosion resistance and smoke toxicity assessment.

• Marking and Identification: Sleeves are marked according to EN 4674-002 with identification codes including size and presence of internal protective tape to aid installation and traceability.

Applications

SIST EN 4674-004:2018 EMI protective sleeves are primarily applied in aerospace electrical systems, specifically for:

• Cable Protection Outside Pressurized Areas: Ensuring cables are shielded from electromagnetic interference in aircraft zones exposed to varying thermal and environmental conditions.

• EMI Shielding in Aerospace Harnesses: Preventing stray electromagnetic energy from corrupting sensitive avionics systems, thereby enhancing operational reliability and safety.

• Durable Cable Bundling Solutions: Offering mechanical protection along with electrical shielding for complex cable bundles, reducing maintenance needs and extending service life.

• Use in Harsh Environmental Conditions: With resistance to fluids, temperature extremes, and mechanical abrasion, these sleeves are suited for demanding aerospace installations.

Related Standards

SIST EN 4674-004:2018 works in conjunction with several related aerospace and electrical standards for comprehensive quality assurance:

• EN 4674-001: Technical specifications for self-wrapping shielding EMI protective sleeves.
• EN 4674-002: General guidance and list of product standards related to EMI protective sleeves.
• EN 2591-214 & EN 2591-307: Test methods covering lightning strikes and salt mist corrosion to ensure material resilience.
• EN 2825 & EN 2826: Burning behavior and smoke toxicity requirements for materials under fire conditions.
• EN 3475 Series: Electrical cable test methods including tensile strength and plating adherence of metallic strands.
• IEC 62153-4-3: Electromagnetic compatibility testing methods focusing on transfer impedance of metallic communication cables.

Together, these standards support the design, testing, and deployment of EMI protective sleeves that meet stringent aerospace industry demands.

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