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Could thick cloud coal dust cause flashover on hi-voltage line

R

RQ

Jan 1, 1970
0
I would like some opinions on this. Visualize the following:


Pressure relief door popping open, thick cloud of coal dust blowing towards
high voltage line. Could this conceivably cause a flash over? Thanks

rq
 
C

Charles Perry

Jan 1, 1970
0
RQ said:
I would like some opinions on this. Visualize the following:


Pressure relief door popping open, thick cloud of coal dust blowing
towards high voltage line. Could this conceivably cause a flash over?
Thanks

rq

A cloud of dust with a high enough concentration of coal dust could cause a
flashover. Do I know what the concentration would have to be? No. Smoke
from brush fires in South Africa has been documented as a cause for
flashovers on transmission lines there. Coal dust is probably more
conductive than smoke particles.

Charles Perry P.E.
 
D

Don Kelly

Jan 1, 1970
0
AJW said:
Dust clouds I think have been known to actually explode under the right
conditions. Coal I suspect in a fine enough dispersion might be a possibility.
Coal is pretty dirty carbon, so it's reasonable to assume it'd be somewhat
conductive. If that's so, I can imagine a discharge propagating through it.
After all, there are lots of sharp edges, and that leads to high field
gradients. When one has a bit of a corona discharge it effectively reduces the
air gap, and cascading could happen.

Or not.
Coal dust has been known to explode. I would suspect that if a spark occurs
and the dust was dense enough, there would be explosive combustion. Flame
stability is a major concern with coal fired steam generators using fine
coal (as dust in an air suspension) - if the flame goes out and fuel is
still being blown in there is a chance of a hot spot igniting the coal or
sudden explosive ignition when the flame returns - bye bye boiler.
It has also happened with flour as well due to static or other sparks. Any
combustable material in a fine enough suspension can explode.
 
A

Andrew Gabriel

Jan 1, 1970
0
In fact you can buy a fine steel wool pad and set it on fire
with a match..it will go up in flames (leaving a small pile of
rust).

There's at least one case of someone having this happen in
a shopping bag, where a steel wool cleaning pad came into
contact with a small 9V battery's terminals.
 
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