junkhound
Senior Member
- Location
- Renton, WA
- Occupation
- EE, power electronics specialty
Was part of the design team for the space station power system back in the early 90's, involved mostly with solar array sequential switching unit and the DC-DC converters.
A few ultra-safety gung ho folks at Huntsville wanted the 'latest' in safety measures, including very 'fancy' GFCI and arc fault detection.
Arc fault in those days was in infancy. (imo still is!)
The AFCI concept then was a full computer designated to run FFT (Fast Fourier Transforms) on the DC distribution system waveforms looking for frequency domain signatures of arcing, corona, or partial discharge down to picoamp levels.
False indications far outnumbered any real arcing (especially in a wiring system built to man rated space standards!) and the 'fancy' GFCI tripped a lot also set to the gung ho folks ultra safety criteria.
Have not worked space station for over 20 years, but have heard that all the 'fancy' computer controlled safety disconnect measures have been 'turned off'.
....... not too many 8 YO sticking paper clips into outlets on space station, and for sure no nails thru NM :lol:
even as much as computer technology has reduced computing sized (aka your smartphone), there is not much chance of a breaker sized unit including enough (at a reasonable cost) to do the level of analysis done for space station waveforms - which still was not sufficient for valid AFCI.
A few ultra-safety gung ho folks at Huntsville wanted the 'latest' in safety measures, including very 'fancy' GFCI and arc fault detection.
Arc fault in those days was in infancy. (imo still is!)
The AFCI concept then was a full computer designated to run FFT (Fast Fourier Transforms) on the DC distribution system waveforms looking for frequency domain signatures of arcing, corona, or partial discharge down to picoamp levels.
False indications far outnumbered any real arcing (especially in a wiring system built to man rated space standards!) and the 'fancy' GFCI tripped a lot also set to the gung ho folks ultra safety criteria.
Have not worked space station for over 20 years, but have heard that all the 'fancy' computer controlled safety disconnect measures have been 'turned off'.
....... not too many 8 YO sticking paper clips into outlets on space station, and for sure no nails thru NM :lol:
even as much as computer technology has reduced computing sized (aka your smartphone), there is not much chance of a breaker sized unit including enough (at a reasonable cost) to do the level of analysis done for space station waveforms - which still was not sufficient for valid AFCI.