Date: Sun, 3 Apr 2011 17:27:37 -0700 (PDT)
From: Roger Parsons <ve3zi@yahoo.com>
Subject: Re: [Amps] what is a 4 wire 240VAC service?
There are a couple of things I don't understand: :-)
(1) When it became clear, probably close to 100 years ago, that 120V was too
low a voltage to efficiently power room (or tubes with handles) heaters and
similar equipment, why did North America not follow the rest of the world and
move to a 230V system? That is, a 3 wire 230V AC service.
&&& The 230 vac Un-balanced service you see in the UK and else where is
actually just a 2 x wire service. Think of it as 230 hot...and a grnded
neutral. It`s sorta like a 120 vac circuit on steroids.
&& They didn`t do themselves any favours with the 50 hz nonsense either. 60
divide by 50 = 1.2 All their pole pigs, etc, have to be 20% bigger .
Ever seen blower specs for both 50 +60 hz operation. Run on 50 hz,
the rpm drops like a rock. and performance sufffers. Any 60 hz plate xfmr,
when run on 50 hz... runs HOT. 50 hz stuff requires way more wire on the
windings, inclusing xfmr`s and stuff like motor windings.
&&& If 50 hz sorta works..and 60 hz is better, they really should have use a
lot higher freq than 60 hz to start with. You set a standard, then build a
national power grid, it`s too late to change to plan B.
&& I read 2 x yrs ago, there is a new standard in the Pro audio
industry..called ... `balanced power` They ended up with 60 vac from each
hot side to neutral. It was recognized by the power co`s too..and has it`s
own sub section
in the electrical code. You can get the same result by running the same audio
gear on 240 vac to begin with....if it`s capable of 240 vac operation.
(2) What bright spark decided that black was a good colour choice for the hot
wire?
&&& who knows, the standards committee is my guess. Telco`s use BLACK for
everything. Each end is well labeled of course.
Actually, there are many other things I don't understand, but those will do for
now.
&&& here`s what I don`t understand. The enviro geeks are all hot for these
silly all electric cars....like the new nissan `leaf`. Each battery is
$18K..and will only be at 80% capacity....after 5 yrs. They have a range of
100 miles....which of course drops to just 60 miles during the summer..with
Air conditioning on. And down to just 40 miles in winter, with heat on. They
haven`t even factored other stuff in..like headlights at night, daytime running
lights, stereo gear, power window`s, moon roof,s power seats, heated seats,
rear window electric defoggers, windshield wipers, etc, etc. They take 22 hrs
to charge up..with a 120 vac outlet.....and 7 hrs to charge with a 40 A 240
vac circuit. the switching supply that puts out 480 vdc is another $2k. ..and
of course requires the 240 vac at 40A circuit. With 9 x homes to a single
50 kva xfmr here in VE7-land...and all with `200 Amp` service...even a few
of these cars plugged in will surely sned our
now overloaded grid into melt down. can u imagine 2-3 of these things
plugged in at your neighbours, next door. Do the Grade 6 maths..... it ain`t
gonna work.
&& Now Tesla motor`s claims their roadster is good for a whopping 350 km on a
single charge...and only requires to be plugged into any 120 vac outlet for
just 2-3 hrs....which of course is pure BS. They claim they can get 300 Hp
and as much torque..from an AC motor..that`s smaller than a 5 x gal paint can.
$43 K for a chevy volt...I don`t think so.
end of rant............ Jim VE7RF
73 Roger
VE3ZI
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