dust

Generally an insulator, or very poor conductor.

Dust most often causes problems by enveloping hot components in an insulating layer, that causes their temperature to rise. It is the temperature that damages the components, not current through the dust.

In high voltage equipment, it may help form carbon tracks that leak current around insulation.

In addition, dust may attract moisture.

Graham

** It is generally an insulator.

But what it " generally" is is a total irrelevance when compared to the monster it can sometimes be.

** By blanketing hot running parts and thereby preventing cool air flow from doing it job - causing overtemp automatic shutdowns and intermittent temporary malfunctions.

Moist or wet dust is a partial conductor, a corrosive agent to metal surfaces and an initiator of high voltage insulation failure.

Very bad news.

Electronics needs to be kept clean.

....... Phil

The answers given by other respondents are all spot on...

If you want to see the effects of dust laden electrical components first hand wait until the first shower of rain after a long dry spell and stand near a high voltage ac power line. You may hear a continuous sizzling, spluttering or crackling sound as the high voltage tracks across the insulators using the moist dust layer as a conductor. At night time you can sometimes see the blue arcs tracking across the insulators. That same dust was there in its dry state before the rain but because it is an insulator it causes no real problems. Add water and the problems begin - pole-top fires and arc-overs etc.

Power distribution organisations will usually embark on a program of high pressure cleaning of pole insulators before the onset of winter to minimise the possibility of hazards from these situations.

And once it is wet it is a conductor, if not a good one.

Sandy

--
Sandy Archer
Reply to newsgroups only