EN 3475-412:2002

Overview

EN 3475-412:2002 is a European standard developed by CEN that specifies test methods for assessing the humidity resistance of electrical cables used in aerospace applications. The standard focuses on evaluating the capability of aircraft cables to withstand hot and humid environmental conditions. It is intended to be used in conjunction with EN 3475-100, which covers general test methods for aerospace cables. Given the critical operational environment of aerospace electrical systems, ensuring cables maintain performance under humidity is vital for safety and reliability.

Key Topics

• Humidity Resistance Testing – The standard defines two levels of humidity resistance tests based on cable application and environmental exposure:

  • Level 1 cables undergo Method A testing, simulating pressurized aircraft areas with conventional relative humidity and operating temperatures greater than 100 °C.
  • Level 2 cables are subjected to Method B, designed for cables exposed to severe environments with high humidity and extended liquid exposure.

• Test Procedures –

  • Method A: Involves winding the cable around a specified mandrel, cycling through 15 phases of 6 hours at 71±2 °C temperature and 90±5% relative humidity, followed by cooling periods. Post-test, cable insulation resistance is measured per EN 3475-303.
  • Method B: Uses a PTFE-coated mandrel where cable samples are wound tightly and secured, conditioned in a climatic chamber at test-specific temperatures and 93±2% relative humidity for periods defined by the cable product standard. After exposure, cables must pass bending and voltage proof tests defined in EN 3475-405 and EN 3475-302 respectively.

• Specimen Preparation – Specific length and insulation stripping requirements ensure uniform test conditions. Minimum specimen length is 750 mm with 25 mm insulation or jacket removed at both ends.

• Test Equipment – The use of a climate-controlled chamber is mandatory, maintaining precise temperature and humidity conditions with distilled or demineralized water to generate humidity.

Applications

EN 3475-412:2002 applies primarily to electrical cables used in aerospace and aircraft systems where humidity resistance is critical for maintaining electrical integrity and operational safety. Typical uses include:

• Aircraft wiring harnesses operating in pressurized environments or exposed to severe weather conditions.
• Cables in avionics systems requiring tested insulation resistance under humid conditions.
• Critical power cables subjected to bending and voltage stress post humidity exposure.

This standard supports manufacturers, aerospace engineers, and quality assurance teams to ensure cables meet rigorous environmental durability requirements, minimizing risk of failure in flight.

Related Standards

• EN 3475-100: General test methods for aerospace electrical cables, used alongside EN 3475-412 to provide baseline procedures.
• EN 3475-303: Specifies insulation resistance testing crucial for evaluating cable integrity after humidity exposure.
• EN 3475-405: Details bending tests at ambient temperature to assess mechanical durability after humidity resistance testing.
• EN 3475-302: Covers voltage proof testing to verify electrical insulation withstand capability post humidity exposure.

Together, these standards form a comprehensive framework for qualifying aerospace cables against environmental and mechanical stressors critical for aerospace safety compliance.

Keywords: aerospace cable testing, humidity resistance, aircraft electrical cables, EN 3475-412, climatic chamber testing, insulation resistance, aviation wiring standards, aerospace electrical safety, environmental durability, cable bending test, voltage proof test, cable qualification