In article <48246bdc$0$657$5a6aecb4@news.aaisp.net.uk>,
Andrew Gabriel cucumber.demon.co.uk> wrote:

In alt.engineering.electrical Andrew Gabriel cucumber.demon.co.uk> wrote:
| In article ,
| "James Sweet" hotmail.com> writes:
|>
|> It's not 110V, it's 240V, we simply split it with a grounded center tap
|> which gives 120V between each side and neutral, or 240V between the sides..
|
| It's the regulation at 120V which people notice.
| If you want to call it a 240V supply, then you
| need to call EU supplies 400V or 415V. That's
| equally misleading.

The effect of loading and how it affects voltage depends on how well balanced
the TWO 120 volts phases are. If they are in balance, then the effect of the
loading on the voltage works as if you were considering the voltage at 240 volts.

If you get a three phase supply, and keep it balanced with the single phase
line to neutral loads, then the voltage regulation is going to be just like you
had loaded it with line-to-line loads, 208 volts in North America and 400 volts
in Europe.

? "Andrew Gabriel" cucumber.demon.co.uk> ?????? ??? ??????
news:48246da4$0$657$5a6aecb4@news.aaisp.net.uk...

In article ,
"Tzortzakakis Dimitrios" writes:

In alt.engineering.electrical Andrew Gabriel cucumber.demon.co.uk> wrote:

| I'm referring to the transformer regulation (and also the LV
| supply cable voltage drop) response to load changes. E.g. if
| I switch on my 10kW shower, that's a 0.1%% change against the
| max load of my 1MVA substation transformer and therefore
| makes no perceivable difference to the voltage in my house.
| If I were to try that on a US 50kVA transformer, that load
| is going to trigger a change of 20%% of the transformer
| regulation, which is much more significant and would
| certainly be visible as a brightness change in light bulbs.

What is the available fault current in these situations?

Tzortzakakis Dimitrios wrote:

So they have developed 100%% efficient transformers?

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Andrew Gabriel wrote:

Mine dim slightly for an instant when my 3 ton heat pump kicks in, it's
only noticeable with the few incandescent lights left in the house
though. The LRA on that thing is something like 90A. I think most of the
drop must be in the 50' or so of 2/0 AL wire between the meter base and
the transformer though as they don't seem to dim at all from any of the
neighbors.

Date: Sat, May 10, 2008, 4:10pm
From: mike.terrell@earthlink.net (Michael A. Terrell)
Tzortzakakis Dimitrios wrote:
The regulation, at least in Europe, is done at 150/15 kV substations and
at the HV side of the transformers, thus at 150 kV. Typical current for
2 x 25 MVA transformers is 150 A, 150 kV and of course secondary at 15
kV, 1500 A. The regulation is done automatically with tap changers,
live. The local transformers at your neighborhood are fixed tap, 15 kV
(they intend to change everything to 20 kV).
      So they have developed 100%% efficient transformers?

In alt.engineering.electrical Michael A. Terrell earthlink.net> wrote:

| The central air kicks on without my lights dimming, and I am in North
| Central Florica.

I bet it's on its own branch circuit, too.