Overview
ISO 2277:1973 - Static invertors for aircraft defines general design and test requirements for 400 Hz static inverters used in aircraft electrical power systems. The standard sets preferred ratings, input supply characteristics, output voltage and frequency, efficiency and stability targets, protection and environmental requirements, identification and marking, and mandatory type and production tests. It is intended to ensure safe, interchangeable, and reliable inverter performance in aviation environments.
Key topics and technical requirements
- Nominal output: 400 Hz; single‑phase nominal 115 V r.m.s.; three‑phase nominal 200 V r.m.s. line-to-line (requirements related to line-to-neutral unless otherwise stated).
- Preferred ratings: Standard VA steps are defined for single‑ and three‑phase units (examples in the standard range from low hundreds of VA up to about 3000 VA) for operation at sea level and +70 °C.
- Input/supply: Designed to operate over Category B input voltage ranges per ISO 1540, tolerate specified transient/overvoltage conditions, and operate with limited source impedance and ripple.
- Efficiency & performance: Minimum full‑load efficiency of 65% at unity power factor; manufacturers declare input currents and worst‑case performance.
- Regulation & stability: Fast regulation on load changes (10–85% and 85–10% load steps) with limited overshoot; modulation and waveform requirements reference ISO 1540.
- Waveform & modulation: Output waveform, modulation envelope, and harmonic/noise performance must comply with ISO 1540 limits.
- Phase sequence & balance: Three‑phase units must be manufactured so normal phase sequence is ABC and reverse operation is not possible; line-to-line and line-to-neutral voltage balance limits are specified.
- Protection: Automatic shutdown options for over/under voltage and frequency, provision for overloads (150% rated current for 100 s) and short-circuit capability (typically 300% rated for 5 s), and reversed‑polarity protection.
- Environmental & cooling: Designed for continuous operation up to 18 300 m (60 000 ft); cooling performance curves required for self‑cooled and forced‑cooled units.
- EMI & magnetic influence: Limits for radiated and conducted interference and requirements to minimize magnetic effects on compasses.
- Testing & marking: Type tests, production acceptance and inspection tests, insulation resistance checks, terminal identification (A, B, C, N; L1/L2), and declarations of performance.
Applications and users
- Aircraft equipment and avionics manufacturers specifying or designing 400 Hz inverters
- Aerospace electrical system integrators and certification bodies assessing compliance with ISO/airworthiness requirements
- Procurement and maintenance organizations selecting interchangeably replaceable inverter units
- Test houses performing type and acceptance testing for avionics power conversion
Related standards
- ISO 1540 - Characteristics of aircraft electrical power systems (referenced for waveform, supply ranges, and limits)
- ISO 2650 series - Environmental and operating conditions for aircraft equipment
- ISO/R 224 - Declaration of performance form (referenced)
Keywords: ISO 2277:1973, static inverters for aircraft, 400 Hz inverter, aircraft inverter design, aviation electrical systems, inverter testing, ISO 1540.