BTS Electronique / Electrotechnique 2005
|
BTS
Electronique / Electrotechnique Session
2005 Dictionnaire
bilingue autorisé. Tout
autre materiel interdit. Your
country needs you Rather
than rebuilding vulnerable electricity grids, Robert Pratt at the
Pacific Northwest National Laboratories (PNNL) at North Richland in
Washington State reckons he has a better way to keep the current flowing.
But if his plan is to succeed, we will all need to do our bit. Pratt
wants to install a special processor chip in every domestic appliance
– washing machines, tumble dryers and so on. Developed at PNNL the
chip monitors the mains supply and if it detects that the grid is
becoming overloaded, it reduces the energy load sucked up by the
appliance. This
small measure could go a long way, lie says. In the US, appliances like
fridges and dishwashers account for about 20% of the grid's electrical
load. The
chip works by sensing fluctuations in the frequency of mains electricity.
In the US, this is usually maintained at 60 hertz, plus or minus 0.03
hertz. But if there is a sudden increase in demand for power, or a
generator fails or there is a major distribution problem, the frequency
can drop below 59.97 hertz. It may only take a few seconds for the
electricity generators to correct this, but that can be enough to shut down
whole sections of the grid. However,
when Pratt's chip senses a drop in mains frequency, it switches off
the appliance. The chip can respond in less than half a second, much
faster than generators can react. Put a chip in every fridge and
dishwasher, and the nation could help keep the grid stable. Initially
the chip will be fitted in plugs so it would only be able to switch an
appliance on or off. But Pratt hopes they will eventually be
integrated into appliances to also adjust power consumption less
crudely – keeping a washing machine's drum tumbling, for example,
but turning off the heating element. He is currently conducting trials
to show manufacturers that the chip won't damage their machines. The
chip could be used to take the strain when supply outstrips demand –
when loads are suddenly removed, for example. In theory, the PNNL chip
could prevent this by switching on dishwashers and washing machines
across the nation to soak up the excess power until the grid recovers.
Who would pay the electricity bill, however, is another matter. New
Scientist. 15 May 2004 377
words I) Compte-rendu en français
(12 points) Mettez en évidence les informations les plus importantes
contenues dans e document (180 mots ±
20%). Indiquez le nombre de mots utilisés. II) Traduction (8 points) Traduisez en français le passage encadré, de "However,
when Pratt's chip..." jusqu'à "... the chip won't
damage their machines."
|