[Lew Hodgett[_6_]]

"Scott Lurndal" wrote:

Most of the class-A office space around (silicon valley) here uses
277VAC
troffers or hanging (indirect) fluorescent fixtures; including the
1970's
vintage building I just moved from as well as the 2008 vintage
building
I'm in now. The efficiency benefits over 120vac are significant in
any
reasonably sized building.
-------------------------------------------------------------
There are many advantages to running a 3 PH,4 wire Y system be it a
480Y277/3PH/4Wire or a 208Y120/3PH/4Wire system.

A grounded "Y" system simplifies the grounding as well as limiting the
fault currents and clearing them when they happen.

Delta systems, (3 wire ungrounded) do not provide these safety
features.

HID and fluorescent lighting systems take advantage of harmonic
flicker which tracks the base phase frequency and when overlapped
minimize the visual flicker with grounded Y systems.

Most large systems gain economic advantages including safety using
480Y277V distribution.

Commercial applications such as shopping centers gain economic
advantages including safety using 208Y120V distribution.

The 120/240V/1PH center tapped secondary distribution is basically for
the residential market where there is no advantage to be gained from
using a 4Wire/3PH system.

Lew
..

[[email protected]]

On Mon, 19 Aug 2013 10:52:34 -0500, Markem
wrote:

On Mon, 19 Aug 2013 09:45:19 -0500, Swingman wrote:

Markem wrote:
On Mon, 19 Aug 2013 09:00:09 -0500, Swingman wrote:

Markem wrote:
On Mon, 19 Aug 2013 06:54:36 -0500, Swingman wrote:

Nope.

In the US the transformer for most residential power taps one of the 3
phases in the power distribution system, which is why it is called
single phase, even though there are 2 hot legs.

The transformer center tap on the pole is grounded and also connected to
a wire called neutral. This provides two output voltages relative to
ground or neutral. Each is 120 V, but they are 180 degrees out of phase
with respect to each other.

Your understanding of electrical things is not very good. I have many
years as an electronic tech. I have tested with an oscilloscope your
theory and proved it wrong. The two legs of a 240V are in phase.

But in the end it really does not matter because everthing electrical
will still work as long as it ain't broke.

Mark

Then you should know the difference between electric and electronic.

I do, do you?

You just think you do ... read the second sentence and weep:


http://en.m.wikipedia.org/wiki/Split_phase

The two halves of the transformer are 180 degrees apart, not the
signal. Question what do you get when you add 120 and -120?

The question is not what you get when you add 120 and -120, the
question is the (potential) DIFFERENCE. Answer; 240V.

[[email protected]]

On Tue, 20 Aug 2013 16:49:40 -0500, Markem
wrote:

On Tue, 20 Aug 2013 17:11:49 -0400, wrote:

On Mon, 19 Aug 2013 14:23:22 -0500, Markem
wrote:

On Mon, 19 Aug 2013 13:52:28 -0500, Swingman wrote:

On 8/19/2013 12:55 PM, Bill wrote:

A relative told me there
were 3 hots at the pole (but he has a factory background, where 3-phase
in the norm).

The power transmission system, that feeds your transformer on the pole
outside your house, is indeed 3 phase, on the _input_ side of the
transformer, as I clearly stated earlier.

Not every where in the United States, the co-op to my house and over
the entire system is single phase, they have only single phase
generators at the power house. But I would bet that my cost per kilo
watt is cheaper that most.

Extremely rare, in the whole north american scheme of things - and
that means you are independent of the national grid.

It is a rural co-op, they're connected to the grid throygh the sub
stations. But they do not provide 3 phase power on the system to the
customers at all. It is a matter of upgrading costing more than the
"customer owners" could pay, and they do not have any large industrail
customers. So my rates are lower than than an Ameren customers in the
local area by quite a bit.

The fact that they don't supply 3-phase to customers doesn't mean they
don't have a 3-phase distribution system. It would be *really*
surprising if you were correct (that they generate single-phase
power). It would be a huge waste of money.

[Kris K. Kaput0]

wrote in message ...

On Mon, 19 Aug 2013 10:52:34 -0500, Markem
wrote:

On Mon, 19 Aug 2013 09:45:19 -0500, Swingman wrote:

Markem wrote:
On Mon, 19 Aug 2013 09:00:09 -0500, Swingman wrote:

Markem wrote:
On Mon, 19 Aug 2013 06:54:36 -0500, Swingman wrote:

Nope.

In the US the transformer for most residential power taps one of the
3
phases in the power distribution system, which is why it is called
single phase, even though there are 2 hot legs.

The transformer center tap on the pole is grounded and also connected
to
a wire called neutral. This provides two output voltages relative to
ground or neutral. Each is 120 V, but they are 180 degrees out of
phase
with respect to each other.

Your understanding of electrical things is not very good. I have many
years as an electronic tech. I have tested with an oscilloscope your
theory and proved it wrong. The two legs of a 240V are in phase.

But in the end it really does not matter because everthing electrical
will still work as long as it ain't broke.

Mark

Then you should know the difference between electric and electronic.

I do, do you?

You just think you do ... read the second sentence and weep:


http://en.m.wikipedia.org/wiki/Split_phase

The two halves of the transformer are 180 degrees apart, not the
signal. Question what do you get when you add 120 and -120?

The question is not what you get when you add 120 and -120, the
question is the (potential) DIFFERENCE. Answer; 240V.

--

All relative to where you are standing. If you stand in the middle and look
west you see a house at 120km away. If you look to the east you another
house 120km away in the opposite direction. If you walk to the west house
and look at the eastern house it is now 240km away and the same direction as
you are looking.

I knew the other 'mercuns wouldn't understand it if I didn't use miles

--

KKK