SIST EN 2349-312:2009

Overview

EN 2349-312:2006 is a CEN / aerospace-series standard that defines a test method for the electrical service life - mixed load of relays and contactors. Intended to be used together with EN 2349-100, this document specifies mounting, loading, measurement and pass/fail criteria for endurance testing of aerospace relays and contactors under mixed load conditions. It applies to component qualification, supplier verification and in-service assessment of switching devices used in aerospace electrical systems.

Key topics and technical requirements

• Test purpose: Determine electrical service life under a prescribed mixed load sequence and detect failures such as contact wear, sticking, blown fuses or excessive contact voltage drop.
• Supply: Loads are switched on (28 ± 1) V d.c. during testing.
• Load sequence:
  • For nominal contact rating < 20 A: 0.5 A resistive, 0.3 A inductive, 0.1 A resistive, then rated resistive load.
  • For nominal contact rating > 20 A: three steps of 10% of rated resistive load, then rated resistive load.
  • For multi‑pole devices the sequence is applied to each pole in turn; each contact switches only one load.
• Timing (one switching cycle):
  • Coil energized: (29 ± 3) s
  • Coil de‑energized: (1,5 ± 0,5) s
  • Total number of cycles: specified in the relevant product standard (EN 2349 product standard).
• Environmental and mounting: Unit mounted and wired per EN 2349‑100, placed in an air‑circulating heating cabinet and tested at the maximum permissible temperature defined in the product standard.
• Monitoring & measurements:
  • Contacts monitored for operation; every defective switching operation = failure.
  • Contact voltage drop measured at each operation; limits are given in the standard (see Table 1 in EN 2349‑312).
  • Housing earth connection must use a fuse rated at 5% of rated resistive contact current (max 3 A); fuse blowing = failure.
• Pass/fail criteria:
  • No electrical or mechanical failure; no sticking/seizing; no blown fuse; contact voltage drop within allowed limits.

Applications and users

• Aerospace component manufacturers and designers validating relay/contactor durability.
• Test laboratories performing qualification, acceptance and batch verification.
• Quality assurance, procurement and certification bodies specifying reliable switching devices for aircraft electrical systems.
• Maintenance and reliability engineers assessing component end‑of‑life behavior.

Related standards

• EN 2349-100 - General requirements (must be used together)
• EN 2349-302 - Insulation resistance
• EN 2349-303 - Dielectric strength
• EN 2349-307 - Contact voltage drop
• EN 2349-412 - Seal

Keywords: EN 2349-312, aerospace relays, contactors, electrical service life, mixed load testing, relay testing procedures, contact voltage drop, switching cycles.