SIST EN 3475-304:2004

Overview

SIST EN 3475-304:2004 is a European standard part of the aerospace series specifying test methods for electrical cables used in aircraft. This part, titled Surface resistance, defines a precise procedure to measure the surface resistance of finished aerospace cables. It is intended for use in conjunction with EN 3475-100, which covers general test methods for aircraft electrical cables.

Developed under the European Committee for Standardization (CEN) and approved by the European Association of Aerospace Manufacturers (AECMA), this standard ensures uniformity and safety in testing aerospace cables. It supports quality assurance by providing a reliable method to assess electrical insulation performance under controlled environmental conditions.

Key Topics

• Scope and Purpose
  Defines testing of surface resistance on completed cable samples to guarantee electrical safety and compliance with aerospace industry requirements.

• Specimen Preparation
  Finished cable samples must be cut to 0.15 meters, carefully cleaned, and handled without contamination to ensure accurate testing.

• Test Setup
  Utilizes electrodes spaced 25 mm apart wound on the cable’s insulation surface. Electrodes are connected to a specialized test chamber designed to control environmental conditions.

• Environmental Control
  Testing requires a controlled atmosphere with relative humidity at 95 ± 5% and stable ambient temperature to simulate operational conditions.

• Testing Procedure

  1. Electrodes soldered to cable conductors with a minimum clearance from the test chamber walls.
  2. A DC voltage between 200 V and 500 V is applied for 1 minute to measure surface resistance.
  3. Then a high voltage AC test (2,500 Vrms, 40-60 Hz) is applied for 1 minute to assess dielectric endurance and absence of surface faults.
  4. After a 15 to 20-minute cooling period, surface resistance is re-measured.

• Pass Criteria

  • No sparking, smoke, burning, or cracking after the high voltage AC test.
  • Surface resistance multiplied by cable diameter must meet or exceed specified minimum values, confirming insulation integrity.

Applications

SIST EN 3475-304:2004 is critical in aerospace electrical wiring manufacturing and quality control processes. Its practical applications include:

• Aircraft Cable Manufacturing
  Ensuring finished cable batches meet electrical insulation standards before installation.

• Aerospace Maintenance and Inspection
  Testing cables during routine inspections or after repairs to verify ongoing compliance with safety requirements.

• Certification and Compliance
  Supporting aerospace certification bodies in validating cable performance in accordance with international industry standards.

• Research and Development
  Providing a standardized baseline for new aerospace cable designs and insulation materials to meet evolving safety criteria.

Related Standards

• EN 3475-100 – Aerospace series – Cables, electrical, aircraft use – Test methods – Part 100: General requirements and test procedures. Essential companion document for general testing conditions.

• AECMA Specifications – Various specifications from the European Association of Aerospace Manufacturers applicable to wiring and electrical systems in aerospace.

• IEC 60502 – International standard covering power cables with extruded insulation applicable to aerospace adaptation.

• MIL-STD-202 – U.S. Military Standard including electrical and environmental test methods related to aerospace and defense cables.

Summary

SIST EN 3475-304:2004 provides a rigorous testing methodology for assessing the surface resistance of electrical cables in aerospace applications. It ensures cables maintain high insulation performance and surface integrity under specified environmental and electrical stresses. Manufacturers and aerospace operators rely on this standard to guarantee the safety, reliability, and conformity of aircraft wiring systems, supporting safe flight operations worldwide.