EN 3475-302:2006

Overview

EN 3475-302:2006 is a CEN/AECMA-STAN European standard that specifies a method for voltage proof testing of finished and in-production aircraft electrical cables. It is intended to be used together with EN 3475-100 (general test methods). The standard sets repeatable procedures to verify insulation integrity and to detect defects that could cause flashover or breakdown in service.

Key procedural elements in the standard include the immersion test, dry spark test, dry impulse test, and voltage testing of cable components (screened cables). The standard defines specimen preparation, test durations, frequency ranges, electrode arrangements and acceptance criteria (no perforation of insulation or jacket).

Key Topics

• Immersion test

  • Specimens: typically 15 m lengths with ends at least 150 mm below solution surface.
  • Test solution (15–25 °C): 30 g sodium chloride, 1 000 g distilled water, 2 g wetting agent.
  • After 1 h immersion, the specified voltage (40–60 Hz) is applied between conductor (or shield) and an electrode in contact with the liquid for 5 minutes.
  • Voltage rise rate: 300 V/s to 500 V/s.
  • Acceptance: no perforation of insulation or jacket.

• Dry spark test (production)

  • Continuous-testing electrode made of chains/metallic feelers to contact the cable surface.
  • Cable speed and electrode length ensure each point is exposed at least 0.20 s.
  • Voltage applied between conductor(s) (or shield) and electrode at frequency 40–60 Hz.
  • Acceptance: no flash-over or perforation; defects trimmed per note.

• Dry impulse test (production alternative)

  • Uses negative pulses with a damped oscillation and controlled waveform parameters.
  • Rise time: ≤ 75 µs (0–90 % of peak). Pulse rate: 200–500 pulses/s.
  • Capacitive load tolerance defined to limit peak voltage reduction.
  • Detection: error circuit must interrupt supply on faults and detect arcs at 75 % of test voltage via a 20 kΩ path.
  • Calibration: voltmeter accuracy and oscilloscope checks required.

• Voltage test of components (screened cables)

  • RMS voltage (40–60 Hz) applied for ≥ 1 min between one component and others (with screen connected together).
  • Acceptance: no insulation perforation.

Applications

• Production-line quality control for aerospace cable assemblies
• Final acceptance testing of finished aircraft electrical cables
• Screening of cable batches to prevent in-service electrical failures

Benefits include improved electrical safety, consistent manufacturing quality, and reduced risk of insulation breakdown in flight-critical systems.

Related Standards

• EN 3475-100 - Aerospace series: Cables, electrical, aircraft use - Test methods - Part 100: General (normative reference).
• Other EN 3475 series parts addressing mechanical, environmental and electrical test methods for aircraft cables.

For implementation, follow EN 3475-302:2006 in conjunction with project technical specifications that state the test voltages and acceptance criteria relevant to the cable design and application.