SIST EN 2349-304:2009

Overview

EN 2349-304:2006 is a CEN aerospace series standard that describes a standardized method for measuring the operate (actuating) time and release (drop-out) time of relays and contactors. It is intended to be used in conjunction with EN 2349-100 (general requirements). The procedure supports consistent, repeatable timing measurements for product qualification and compliance in aerospace electrical systems.

The standard defines when timing starts and stops, the electrical loading conditions for test contacts, and basic recording practice. A typical test circuit is shown in the standard (Figure 1) and specific timing characteristics are illustrated in Figures 2 and 3.

Key Topics

• Operate time definition: Measured from the application of the rated coil voltage to the instant the last normally‑open (NO) contact closes. Operate time is evaluated excluding contact bounce.
• Release time definition: Measured from removal of the rated coil voltage to the instant the last NO contact opens, or for changeover contacts to the instant the last normally‑closed (NC) contact closes (includes transfer time). Release time is evaluated excluding bounce.
• Contact load and test voltages:
  • Contact load during timing: 5 mA to 100 mA
  • Open contact voltage for relays/contactors up to and including 25 A rating: 6 V d.c. max
  • Open contact voltage for relays/contactors above 25 A rating: 28 V d.c.
• Test repetition for qualification: For qualification tests, five measurements shall be taken and recorded to demonstrate repeatability.
• Reference illustrations: The standard references Figures 1–3 for the typical test circuit, switch action, and timing/bounce characteristics.

Applications

EN 2349-304:2006 is applicable to aerospace component manufacturers, test laboratories, and procurement teams needing a harmonized method to verify relay and contactor timing. Practical uses include:

• Qualification testing of electromechanical relays and contactors for aircraft systems
• Production or acceptance testing to confirm timing performance against product standards
• Comparative evaluation during design validation and supplier assessment

Benefits include improved repeatability, clearer pass/fail criteria for timing, and alignment with broader aerospace test suites when used alongside EN 2349-100.

Related Standards

• EN 2349-100 - Aerospace series: General requirements for relays and contactors (to be used together with EN 2349-304)
• ISO 2678 - Environmental tests for aircraft equipment: Insulation resistance and high voltage tests (normative reference listed)

For implementation, follow the specified measurement start/stop points, use the defined contact load and open contact voltages, and document the five qualification measurements. The standard focuses on timing measurement method and does not replace product-specific timing limits, which are given in the applicable product standard.