oSIST prEN 3475-805:2023

Overview

The oSIST prEN 3475-805:2023:2023 standard is part of the Aerospace series focusing on electrical cables for aircraft use. It specifies standardized test methods for measuring the characteristic impedance of aerospace cables. Developed under the auspices of CEN and ASD-STAN, this document updates and supersedes the previous EN 3475-805:2002 standard, incorporating references to EN 50289-1-11 for electrical test methods.

Characteristic impedance measurement is essential in aerospace electrical cable testing to ensure consistent cable performance and compatibility with avionics systems. This standard provides detailed procedures for various measurement techniques tailored to coaxial and shielded symmetrical cables commonly used in aircraft.

Key Topics

• Scope and Normative References: Establishes test methods based on EN 50289-1-11 and related aerospace standards such as EN 3475-100 (general test methods) and EN 3475-804 (velocity of propagation).

• Test Specimen Preparation: Details how cable samples must be stripped and prepared for accurate measurement connectivity.

• Measurement Methods:

  • Method A: Uses an impedance bridge on coaxial cables with open- and short-circuit terminations to calculate characteristic impedance.
  • Method B: Employs a reflectometer measurement technique in accordance with velocity of propagation test setups, calculating impedance from reflection coefficients.
  • Method C: Applies to shielded symmetrical cables using a vector network analyzer and a balun device to perform reflection measurements, with calibration steps to account for test setup impedance.

• Formulae and Calculations: Clear mathematical formulas are provided for deriving characteristic impedance from input impedance and reflection coefficient measurements.

• Equipment Requirements:

  • Impedance measuring bridge
  • Reflectometer and oscilloscope
  • Vectorial network analyzer and balun for shielded symmetrical cables

• Compliance Criteria: Test results must comply with product-specific impedance limits set out in relevant aerospace product standards.

Applications

• Aircraft electrical cabling manufacturing and quality control
• Aerospace system integration ensuring cable compatibility and minimizing signal distortion
• Validation of cable production batches to meet strict aerospace impedance standards
• Troubleshooting and maintenance of aircraft wiring systems by verifying characteristic impedance
• Compatibility verification with avionics systems to prevent signal reflection and interference in aircraft communication and control systems

By adhering to oSIST prEN 3475-805:2023, manufacturers and engineers can ensure that aerospace electrical cables meet precise impedance specifications, contributing to reliable and safe aircraft electrical performance.

Related Standards

• EN 3475-100: Aerospace series - cables, electrical, aircraft use – general test methods
• EN 3475-804: Test methods focusing on the velocity of propagation in aerospace cables
• EN 50289-1-11: Communication cables – electrical test methods including characteristic impedance, input impedance, and return loss measurements

These linked standards form a comprehensive framework governing the design, testing, and certification of electrical cables for aerospace applications, supporting high reliability and safety standards critical to the aviation industry.

Keywords: Aerospace cables, electrical cable testing, characteristic impedance measurement, aircraft cable standards, oSIST prEN 3475-805:2023, EN 50289-1-11, reflectometer test, impedance bridge, vector network analyzer, shielded symmetrical cable, avionics cable testing compliance.