High level arc fault detector

An arc fault detector for detecting arc faults in three phase aircraft power systems;

• comprising:
• means for generating three load currents in the three phase system, where each load current in the three phase system is indicative of each of the three phases;
• means for rectifying the generated load currents;
• mean for comparing the three rectified load currents;
• means for generating a signal in response to the three rectified load currents differing for a time period exceeding a predetermined duration;
• and
• means for detecting that one of the three rectified currents exceeds a predetermined threshold, wherein the means for generating a signal in response to the three rectified load currents differing for a time period exceeding a predetermined duration generates a signal if at least one of the three filtered load current exceeds the predetermined threshold.

A method of detecting arc faults in three phase aircraft power systems, comprising:

• detecting when at least one of the three load currents in the three phase power system has a current exceeding a predetermined threshold;
• detecting differences between the three load currents;
• and
• generating a signal indicative of differences being detected between the three load currents for a time period exceeding a predetermined duration;
• wherein the detecting differences comprises generating load currents in the three chase system, each load current indicative of one of the three phases and generating a signal indicative of at least two of the three load currents differing by more than a predetermined amount, and detecting differences further comprises continuously monitoring the load currents indicative of the three phases.