SIST EN 2349-309:2009

Overview

EN 2349-309:2006 is a European aerospace series standard that defines a method to test exported spikes (outgoing interference voltage) generated by internally suppressed relays and contactors when the coil is de‑energized. Published by CEN/ASD‑STAN, the standard is intended to verify that transient voltages produced at the device output do not exceed limits specified in the applicable product standard. EN 2349-309 is to be used together with EN 2349-100 (General requirements).

Key topics and requirements

• Scope: Applies only to internally suppressed relays and contactors; focuses on outgoing interference voltage produced during coil turn‑off.
• Pre‑test conditioning: The maximum coil voltage must be applied with reversed polarity to coil terminals for at least 2 seconds before interference tests to ensure correct inverse voltage conditions.
• Test counts:
  • Acceptance testing: 1 test
  • Qualification testing: 3 tests
• Measurement equipment: An oscilloscope is required for type (qualification) testing to capture transient waveforms.
• Waveform characterization: The standard describes typical timing points (T1–T5) on the outgoing voltage curve (e.g., contact opening/closing, armature movement start/end, spike peak) to aid interpretation of transient events.
• Pass/fail criterion: The outgoing interference voltage must not exceed the limit established in the product standard for the device under test.

Applications and practical value

EN 2349-309 is practical for:

• Aerospace relay and contactor manufacturers - to verify suppression designs and demonstrate compliance with exported spike limits during product development and qualification.
• Test laboratories - to perform standardized outgoing spike measurements, produce reproducible oscilloscope captures, and support certification.
• Avionics and systems engineers - to assess risk of electromagnetic interference (EMI) from switching devices and to select properly suppressed relays/contactors for aircraft electrical systems.
• Quality assurance and procurement teams - to define acceptance test requirements and ensure delivered components meet interference specifications.

Using this standard helps reduce unexpected EMC/EMI issues in aircraft systems by ensuring switching transients are controlled and documented.

Related standards

• EN 2349-100 - Aerospace series - Requirements and test procedures for relays and contactors - Part 100: General requirements (to be used in conjunction with EN 2349-309).
• Aerospace EMC and product-specific standards may reference or require outgoing spike testing as part of overall compliance.

Keywords: EN 2349-309, exported spikes, outgoing interference voltage, relays and contactors, aerospace standard, testing procedures, EMC, internally suppressed relays.