On Sun, 15 Jun 2008 01:27:05 -0700 (PDT) email@example.com wrote:
| firstname.lastname@example.org wrote:
|> The design I was thinking of would, first of all, including a round
|> "ground shell". That would be a metal shield (for arc safety) around
|> the blades, and also serve as the protective ground. Think of the DIN
|> connector used on older PC keyboards, but a bit larger, with 2 blades
|> much like the UK plug. But the shell serves as the ground.
| I'd actually thought of the same "ground shell" idea, but not in quite
| the same way. There is another advantage to it in that it prevents
| live pins being touched, and therefore removes the need for shrouded
| pins, as on BS1363. Also, if the shell was a tight fit in the socket
| it would prevent the 'wobble' problem, and the pins could be placed
| closer together to avoid increasing the overall size of the plug.
|> With the blades oriented left/right, there would be an indentation
|> notch on the left and right sides for 100-127 volt systems, and on
|> the top and bottom (away from the blades) for the 200-254 volt systems.
|> A universal plug for equipment that can take either voltage would not
|> have the indentation notch.
| This sounds the wrong way round; surely a 'universal' plug would need
| notches in both positions?
The notches are a lock-OUT mechanism. The outlets would have a full
round ring that would accept the presense of the notch for that voltage.
The other way around, with the universal having BOTH notches, then an
outlet has to be able to accept BOTH notches for a universal plug to
work. To prevent the single voltage plugs from being inserted, then
the outlet design would have to block the lack of a notch. While this
can work, it would require tighter construction tolerange to be sure
someone cannot force the wrong plug in.
| I think you're talking about the notches being in the shell; is that
|> The outlet would have a ring hole to accept the shell. There would
|> be a key hole to accept the indentation notch in the appropriate
|> position for the particular voltage system it provides. The universal
|> plug could fit either outlet. But the volatage specific plugs would
|> only fit the appropriate outlet because the indent in the shell would
|> block the entry of the plug. If you turn the plug to make the indent
|> fit, the pins would be 90 degree off.
| Ah, I think its the other way round, with the keys on the plug fitting
| into notches in the socket, is that correct?
These would be keys to block insertion for the wrong voltage plug in the
design I suggested.
| It actually sounds like you've invented something not too far removed
| from the old BS196-1961 'Reyrolle' industrial plugs which were quite
| common at one time, but seem to have largely died out now. I think
| the last time I saw a totally new installation with them was on the
| Bank Extension of the Docklands Light railway, maybe 15 years ago.
| They were available in 5, 15 and 30A sizes, and in various keyings and
| colours for different Voltages, number of phases, grounding
| arrangements etc. I seem to remember that the use of these had been
| totally banned somewhere, Australia and/or New Zealand I think but I
| don't know why. There were fused versions available, where the fuses
| were the pins, as on the old D&S plugs, and could simply be unscrewed
| to replace, without having to open the plug.
There are the larger IEC 309-1 and 309-2 plugs and outlets. These come in
a number of different voltage and current configurations and have more
complex keying to lock out wrong connections.
My idea is a smaller set of these, with the shell around the pins being metal
and serving as the ground. One smaller pair for low current (15 or 16 amp)
and a somewhat larger set (slightly larger shell, thicker pins) for higher
current (30 to 32 amp). The shell might have a pin spacing of 1cm and a shell
diameter of 2.4cm, while the next size up is 1.5cm and 3.6cm. Beyond that,
go with the existing IEC 309-1/2 ones.
Note that my design allows for 180 degree plug rotation, and requires that no
appliance connect either current carrying conductor to any human contactable
metal surface (including the shell of an Edison style screw lamp base). These
are requirements also seen in Germany for the rotatable Schuko (as well as the
reversable Europlug). My design would also require anything taking 200-254
volts to accept it as 200-254 volts relative to ground (single ended) as is
common in most of the world, or as 100-127 volts in two opposite polarities
(double ended) to get 200-254 volts, as is common for 240V in North America.
My design does not address the 50/60 Hz issues, or the possibility for usage
of DC. Potentially it could be made more complex to deal with those things.
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