okay so we've seen when we've created a serial arc that we couldn't manage to actually make an
arc that was a bad arc that caused the AFDD to operate now you've said to me David that you can
create an arc is that true i can uh with the the aid of my 10 kilovolt transformer here this is a
neon transformer for powering neon signs made by an Italian company called
FART uh i don't know what it stands for it stands for something in Italian but that's their name
um so it's going to put out uh around 10 000 volts obviously ac because it's transformer
uh very low current i think it's only rated at like 37 milliamps or something like that but
it's a very high voltage obviously it's going to step up the 230 volts to 10 kilovolts and that's
going to go to two prongs here to electrodes and anode in the cathode um and we should see some
fiery effects between them okay let's let's go live without them plug in and stand back
wow doctor i'm at brown time yeah so there's a a rising arc we'll have to have a look at
why that's rising and how it's being generated well i'm going to go with it with the
front cover removed so you can see okay see what's going on there now
that's fantastic we're watching it on the big screen as well as here so as
you're looking on the camera from here we're looking at over there and that's a fantastic
looking driving arc sounds great it does 1.21 gigawatts i think it was a sticky
so we unplugged that now so we're going to turn it off so can we turn it off now please
please no we're going to take the cover off okay then so we've removed the glass and we should
be able to see the art from its base point rise all the way up so what's going on there then for
us David first of all um what we have here are actually two barbecue skewers much their wives
annoying she wasn't able to make her kebabs that day and they're rather amateurishly stuck through
this um carpenter's modesty block onto what is actually a a spare tile from when i retired my
downstairs loo okay so it's all uh all very um valuable information together on a very hungover
Sunday with whatever materials were to hand but the exception of course the transform that was
bought specifically for the job so um the the output of the transformer just goes to these two
two skewers and we can see that there's a very small air gap at the bottom obviously we got um
they're the only contact between the skewers is both the plastic block that holds them in place
and the the air both of which have a uh a high insulation resistance yes if we were to take our
multi-function tester our mega fluke whatever and do an IR test by connecting them to these prongs
um we would see that it would go off scale high because the resistivity of the air and the plastic
is such that they're not actually connected together exactly so it's not going to jump the gap
but if we bump that voltage up more than the the test equipment can put out so more than
the thousand volt scale like they normally go to being bumped up to 10 000 volts and what we'll
actually do is we'll break down the resistivity of the air and what you'll see at the bottom here
is a bright blue flash as the resistivity of that air breaks down and the the voltage arcs across
uh between the two prongs as soon as it arcs across it it effectively short circuits the
transformer so the voltage level drops the current rises as the current path opens and we
um electrify the air and what we end up with is a a rising plasma arc uh a
hot air arc yes that because of the heat of it because the shape of these prongs
will rise up the thing and then obviously eventually snap at the top and the process begins
again yeah we go again okay so we're stepping back and see what we've got here
you can hear the snap as that blue spark forms across the bottom
as the uh the air originally initially breaks down and you can see that not all of them get to
the top but at the point of which it does break it starts to process again so watch and see how
many get to the top how many stopped before the top and two that one didn't that one did
obviously the higher up it gets the harder it is for the arc to maintain because it's having
to cross a wider gap of larger resistance that's fantastic well at least that's my
understanding anyway but my GCSE physics was appalling in a very long time ago so
don't worry but you could tell me joe would have stepped in if we were wrong we're okay
that's just yeah we weren't doing that today until David came yeah and again this this won't
trouble your circuit breaker because it's just a load for the transformer um there's no overload
on the incoming supply to it it won't trouble your RCD because it's not a fault to work
and it won't trouble your AFDD because it's not on the distribution wiring it's
isolated by the transformer to the load side so even if you have an AFDD and you have some
kind of fault on the load side that's isolated from the supply by a transformer transformer up
to isolate or anything like that the AFDDs just not going to notice it you can leave it again for
longer you can actually smell the the ionized air because it's ionizing the air as it's uh
it's immune it smells like a like a photocopy if you're close to a photocopier or laser printer
just bad for the environment