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With a growing demand for passenger entertainment, communication and device charging, aircraft power systems are also growing in scale and complexity.

The complexity is increased further by changes in aircraft primary electrical power from a fixed 400Hz at which aircraft generators traditionally worked, to varying frequencies from 400Hz up to 800Hz.

Added to the need for measurement accuracy at frequencies specific to avionics, is an associated demand for harmonic voltage and current measurement over a range and at an accuracy required by avionic standards such as DO160.

Frequency range

Given the understandable objective to minimise weight, Avionic power systems have always operated at a higher frequency than ground-based power systems. The original and most used frequency in avionic power systems is 400Hz, with higher frequencies up to 800Hz being used in more modern aircraft.

This introduces a challenge in relation to power measurement, since most power measurement instruments focus their optimum accuracy band in the 50/60Hz frequency range.

Designed with avionic applications in mind, N4L power measurement instruments combine wideband measurements up to 2MHz including all Avionic harmonic frequencies and a wider optimised accuracy band from 40Hz to 850Hz.

50/400/800Hz avionics power systems

Harmonic requirements

harmonically distorted waveform

Avionic standards pay considerable attention to harmonic distortion, which go way beyond ground-based harmonic standards both in harmonic frequency, due to higher fundamental frequency and in harmonic number, where avionic standards require harmonics of up the 417th order.

Accuracy both of harmonic magnitude and phase are defined and a max hold function is required, so that highest recorded harmonics can be observed.


While positional sensor technology continues to develop, the accuracy and reliability of non-contact magnetic displacement sensors ensures that they remain a trusted method by which to identify position critical components in aviation.

N4L phase sensitive multi-meters in Vector Voltmeter (Phase Angle Voltmeter) mode specifically address the in-phase and quadrature voltage component measurements typically used for the design and test of LVDT or other magnetic displacement sensing devices.

Linear Variable Transformer schematic