Author Topic: Prozone G-PZ80 air fresheners- internal charring  (Read 3179 times)

Offline kurnal

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Prozone G-PZ80 air fresheners- internal charring
« on: August 10, 2009, 10:23:12 PM »
I have come across a mains powered air freshener that generates ozone by creating a controlled high voltage corona discharge on a special discharge card  and dispersing the resulting ozone using a small fan. They are widely used in care homes.
A small smouldering fire occurred in one of these units and when I examined two others found signs of charring inside.

I have taken some photos and am forwarding them with a letter to the manufacturers.

It would appear that unwanted  corona discharge has taken place between the  high voltage discharge card terminal and the low voltage motor feed. This has at first led to tracking which has then  developed further to carbonise the plastic base of the unit between the two terminals ultimately becoming conductive thus setting up an easier path for further tracking and as the discharge current increases the heat produced increases till eventually the area glows incandescent and considerable heat is generated.

It would appear that the plastic itself is self extinguishing and once the power fails the heat will diminish.

I examined two other identical units, one of which was in operation at the time of inspection. Neither had an excessive build up of dust or any signs of damp or humidity. Both did have orange stains around the red feed to the fan motor, and signs of black tracking between the two terminals, one in a much more advanced than the other. The black tracking in the least affected unit had the appearance of “whiskers”.

Has anyone else encountered problems with these units please?