Re: 50 hz VS 60 hz and a 120 HZ question


"Jon Elson" <elson@xxxxxxxxx> wrote in message
news:4728E7EA.6060105@xxxxxxxxxxxx


F. George McDuffee wrote:
On Tue, 30 Oct 2007 09:01:36 -0500, Randy <rbraun333@xxxxxxxxx>
wrote:


This group seems to have alot of electrical knowledge, sooo.....

The US is 60 HZ and Europe is 50 HZ, a 60HZ motor is more efficient,
so, what would happen if the US or the world for that matter would
switch to 120 HZ or maybe even as high as 400HZ (which is common in
aircraft). Motors and transformers would be much more efficient,
power savings could be enormous, both in transmission and use.

<snip>
=========
what a group! thread hijack [sort of]

Given the increased efficiency in terms of both size and power,
how would 3 phase residential power service (in new homes) affect
power distribution cost/efficiency and the life-cycle cost of
high reactive consumption units such as residential air
conditioners and possibly refrigerators if these were 220
3-phase?
The really big advantage of a 3-phase hermetic refrigeration
compressor
is it needs no starting relay. Just apply power and the motor spins
up.
I doubt there is a great increase in efficiency of small 3-phase
motors over single phase. If you want REAL efficiency gains,
permanent-magnet synchronous motors run by variable frequency drives
do show large gains in efficiency. All variable-speed air
conditioners use some sort of VFD, and permanent magnet motors are now
replacing the induction motor, as they ARE more efficient.

The liklihood of the US adopting 3-phase wall outlets for all
appliances is about as high as (your favorite never-will-happen
scenario here).
There would be REAL costs to extending 3-phase power to all
residences, and putting in 3-phase meters and 3-pole breakers in the
panels. With a basement full of machine tools, I'd love it, though.
I do NOT have 3-phase power on my pole, but it is "only" a block away.

I can just imagine having a 5-prong Harvey Hubbell twist lock plug on
those lamps with three bulbs and a 1-2-3 switch on them!

Jon
With 3 phase distribution you would not have 5-prong Harvey Hubbell
twist lock plug on your lamps.

In this country (Australia) 3 phase is available in most places but only
delivered to those homes that need it for Air con and such bigger loads.
Small things, lamps etc still run of one simple plug similar in size to
the US 120volt plug. The area served by a pole transformer or roadside
box seems to be larger than is common in the US but the single pase
homes are distributed across the three phases. Pole pig outside my house
was changed last week from 40KW to 60 KW (I think).

And Gloat!! I could have 3pahse in my workshop if I needed it but a
table saw is the biggest thing I have.

John G.


.

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