Searching \ for '[OT] Saftey issues: AC vs DC' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/power.htm?key=ac
Search entire site for: 'Saftey issues: AC vs DC'.

Exact match. Not showing close matches.
PICList Thread
'[OT] Saftey issues: AC vs DC'
2003\04\26@093408 by John Pearson

flavicon
face
Is it true that DC is more dangerous, electrocution wise, than AC.

Is it true that some countries use DC?

If so, what is the voltage?

Thanks

John

--
http://www.piclist.com hint: To leave the PICList
spam_OUTpiclist-unsubscribe-requestTakeThisOuTspammitvma.mit.edu>

2003\04\26@135159 by Tal

flavicon
face
The main problem with DC is that it is difficult increase/decrease its
voltage and therefore, it cannot be transmitted efficiently over long
lines (the old Edison vs Westinghouse debate
http://www.raintaxi.com/online/1997fall/bloodvolts.shtml). AC allows you
to transfer the same amount of electrical power with less loses on the
wires(high voltage, low current).

There are special cases when high power DC system are used (e.g.
conventional submarines with huge banks of batteries and voltages in the
range of hundreds of volts) but I don't think any country uses DC for
power transmission.

As for danger, I think that if you compare DC and AC of the same voltage
rating, AC is more dangerous because the actual momentary voltage can go
higher than the DC. This is because the AC voltage rating is typically
done by RMS which is kind of a average and is lower than the max peak
voltage.

Hope this helps,

Tal

> {Original Message removed}

2003\04\26@135614 by David VanHorn

flavicon
face
> I don't think any country uses DC for power transmission.

Except for a couple 0.5MV systems, you're right.

--
http://www.piclist.com hint: To leave the PICList
.....piclist-unsubscribe-requestKILLspamspam@spam@mitvma.mit.edu>

2003\04\26@140241 by Wouter van Ooijen

face picon face
> There are special cases when high power DC system are used (e.g.
> conventional submarines with huge banks of batteries and
> voltages in the
> range of hundreds of volts) but I don't think any country uses DC for
> power transmission.

AFAIK AC can not be used for very long lines, for instance in Sweden
between the power generation (in middle and north of the country) and
the use (mainly in the south).

Wouter van Ooijen

-- -------------------------------------------
Van Ooijen Technische Informatica: http://www.voti.nl
consultancy, development, PICmicro products

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestspamKILLspammitvma.mit.edu>

2003\04\26@140441 by Mike Hord

picon face
I was always taught that high-voltage DC is the more dangerous, because AC
causes muscle spasms and DC causes muscle contraction, therefore you're less
likely to be able to let go of something that's shocking you if it's a DC
source.

I once saw a guy connect 60+ 9-volt alkaline batteries through the palms of
his hands.  He had to jump up and down until they fell out of his hands,
because his hands and arms clamped down so tightly.

Another use of high voltage DC may come around soon:  I've heard of
streetcars which use large banks of low voltage, high capacitance (2000+
Farad) capacitors in series to store energy when slowing down, then use that
energy to help speed back up.

Mike H.

{Quote hidden}

> > {Original Message removed}

2003\04\26@143216 by Thomas C. Sefranek

face picon face
> -----Original Message-----
> From: pic microcontroller discussion list
> [@spam@PICLISTKILLspamspamMITVMA.MIT.EDU]On Behalf Of Tal
> Sent: Saturday, April 26, 2003 1:50 PM
> To: KILLspamPICLISTKILLspamspamMITVMA.MIT.EDU
> Subject: Re: [OT] Saftey issues: AC vs DC
>
> AC allows you
> to transfer the same amount of electrical power with less loses on the
> wires(high voltage, low current).

Tell me pray, what special properties of AC allow for this belief?
Are you saying ohms law applies differently to AC as opposed to DC?
Think about it, if I have the SAME voltage (high) and current why is there
any difference?

> There are special cases when high power DC system are used (e.g.
> conventional submarines with huge banks of batteries and voltages in the
> range of hundreds of volts) but I don't think any country uses DC for
> power transmission.

Better look again!  Here in the North East, we import DC from Canada,
and convert it to AC locally.  I'm talking Multi-megawatts.

> As for danger, I think that if you compare DC and AC of the same voltage
> rating, AC is more dangerous because the actual momentary voltage can go
> higher than the DC. This is because the AC voltage rating is typically
> done by RMS which is kind of a average and is lower than the max peak
> voltage.

Again, another pseudo-science...
The peak voltage is not the deciding issue.
The physiological effects of AC vs DC ARE!
Muscle contractions (Heart beats) are arrested with enough AC applied.
DC of the SAME value heats the same, (Hurts more) but is not as likely to
arrest the heart.
>
> Hope this helps,
>
> Tal


 *
 |  __O    Thomas C. Sefranek   RemoveMEWA1RHPTakeThisOuTspamARRL.NET
 |_-\<,_   Amateur Radio Operator: WA1RHP
 (*)/ (*)  Bicycle mobile on 145.41, 448.625 MHz

hamradio.cmcorp.com/inventory/Inventory.html
http://www.harvardrepeater.org

--
http://www.piclist.com hint: To leave the PICList
spamBeGonepiclist-unsubscribe-requestspamBeGonespammitvma.mit.edu>

2003\04\26@145537 by Jon M (Mike) Jones

picon face
If I remember correctly, as you increase AC voltage past about 450Kv on long
haul lines
the power loss due to radiation  becomes greater than the loss due to
resistance on a similar
length DC line. The last I heard there were at least a couple of these DC
transmission lines
in the west as well.

Mike Jones

----- Original Message -----
From: "Thomas C. Sefranek" <TakeThisOuTtcsEraseMEspamspam_OUTCMCORP.COM>
To: <RemoveMEPICLISTspamTakeThisOuTMITVMA.MIT.EDU>
Sent: Saturday, April 26, 2003 11:30 AM
Subject: Re: [OT] Saftey issues: AC vs DC


> > {Original Message removed}

2003\04\26@150349 by Herbert Graf
flavicon
face
> The main problem with DC is that it is difficult increase/decrease its
> voltage and therefore, it cannot be transmitted efficiently over long
> lines (the old Edison vs Westinghouse debate
> http://www.raintaxi.com/online/1997fall/bloodvolts.shtml). AC allows you
> to transfer the same amount of electrical power with less loses on the
> wires(high voltage, low current).
>
> There are special cases when high power DC system are used (e.g.
> conventional submarines with huge banks of batteries and voltages in the
> range of hundreds of volts) but I don't think any country uses DC for
> power transmission.

       While you are correct on the main disadvantage of DC there are two MAJOR
disadvantages for AC. Those are: the skin effect, and coupling to ground.
       The skin effect requires a larger diameter conductor for a given current
flow then with DC current. This cost is mostly upfront.
       Coupling to the ground is an effect which results in power loss to the
earth.

       Both these advantages CAN result in DC actually being beneficial for very
long high power runs. There is DC transmission in existence. I don't know
about the states but here in Canada we have a high voltage DC transmission
line from our James Bay project. I'm sure other areas of the world also have
DC runs. Wherever you have a VERY remote source of power (1500km+?) you are
likely to see DC used these days versus AC.

> As for danger, I think that if you compare DC and AC of the same voltage
> rating, AC is more dangerous because the actual momentary voltage can go
> higher than the DC. This is because the AC voltage rating is typically
> done by RMS which is kind of a average and is lower than the max peak
> voltage.

       IIRC (and I might be way off here) DC tends to cause muscles to contract.
This is bad because it'll pull your hand closed around a conductor you are
touching. AC tends to just "modulate" the muscles, meaning you are thrown
back. These effects however change at different voltages, I think. TTYL

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestEraseMEspam.....mitvma.mit.edu>

2003\04\26@150355 by Herbert Graf

flavicon
face
> Another use of high voltage DC may come around soon:  I've heard of
> streetcars which use large banks of low voltage, high capacitance (2000+
> Farad) capacitors in series to store energy when slowing down,
> then use that
> energy to help speed back up.

       I've never heard of that. In Toronto, our streetcars, IIRC, just dump the
power they generate while breaking back into the power line, this allows
other streetcars to use that power. Our subways do the same sort of thing,
they break mostly with the motors, the power generated put into the power
rail so that other subways can use it. Of course "conventional" breaks are
also present, and are used for the final few seconds of stopping. TTYL

PS. We also have a line that uses LIMs, their emergency breaks are great big
electromagnets that clamp down on the running rails! Those things can stop
quite literally on a dime.

--
http://www.piclist.com hint: To leave the PICList
EraseMEpiclist-unsubscribe-requestspammitvma.mit.edu>

2003\04\26@150559 by Herbert Graf

flavicon
face
> > AC allows you
> > to transfer the same amount of electrical power with less loses on the
> > wires(high voltage, low current).
>
> Tell me pray, what special properties of AC allow for this belief?
> Are you saying ohms law applies differently to AC as opposed to DC?
> Think about it, if I have the SAME voltage (high) and current why is there
> any difference?

       He is referring to the fact that with AC it is relatively trivial to
transform it to a higher voltage, resulting in fewer losses. These days
however the conversion of DC to higher voltages isn't as hard anymore and
high voltage DC transmission lines definitely do exist. TTYL

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestEraseMEspamEraseMEmitvma.mit.edu>

2003\04\26@150755 by Herbert Graf

flavicon
face
> > Another use of high voltage DC may come around soon:  I've heard of
> > streetcars which use large banks of low voltage, high capacitance (2000+
> > Farad) capacitors in series to store energy when slowing down,
> > then use that
> > energy to help speed back up.
>
>         I've never heard of that. In Toronto, our streetcars,
> IIRC, just dump the
> power they generate while breaking back into the power line, this allows
> other streetcars to use that power. Our subways do the same sort of thing,
> they break mostly with the motors, the power generated put into the power
> rail so that other subways can use it. Of course "conventional" breaks are
> also present, and are used for the final few seconds of stopping. TTYL
>
> PS. We also have a line that uses LIMs, their emergency breaks
> are great big
> electromagnets that clamp down on the running rails! Those things can stop
> quite literally on a dime.


       Please replace the word "break" with "brake" in all instances in the above
message... :( TTYL

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestspam_OUTspamKILLspammitvma.mit.edu>

2003\04\27@043541 by Alex Holden

flavicon
face
On Sat, 2003-04-26 at 20:03, Herbert Graf wrote:
> line from our James Bay project. I'm sure other areas of the world also have
> DC runs. Wherever you have a VERY remote source of power (1500km+?) you are
> likely to see DC used these days versus AC.

ISTR reading somewhere that we (the UK) import quite a lot of power from
France through the Channel Tunnel using a HVDC transmission line.

--
------------ Alex Holden - http://www.linuxhacker.org ------------
If it doesn't work, you're not hitting it with a big enough hammer

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@111528 by Bob Ammerman

picon face
DC is used for very high voltage (1 MVolt+!) long distance power
transmission. For one thing, it avoids the skin effect.

Bob Ammerman
RAm Systems

----- Original Message -----
From: "Tal" <RemoveMEtalTakeThisOuTspamspamZAPTA.COM>
To: <EraseMEPICLISTspamspamspamBeGoneMITVMA.MIT.EDU>
Sent: Saturday, April 26, 2003 1:49 PM
Subject: Re: [OT] Saftey issues: AC vs DC


{Quote hidden}

> > {Original Message removed}

2003\04\27@112942 by Jim Dewar

flavicon
face
one safety issue around AC vs DC.... if you have arcing, AC is self extinguishing (zero crossings of sine curve). DC is not. DC will continue to arc until you shut it off.
DC (600 vdc) seems to be (not sure why) the choice for electric busses and trains around here (western canada).

jim.

On Saturday 26 April 2003 04:09 pm, you were heard to utter:
{Quote hidden}

> > > {Original Message removed}

2003\04\27@165222 by William Chops Westfield

face picon face
   one safety issue around AC vs DC.... if you have arcing, AC is self
   extinguishing (zero crossings of sine curve).

I seem to recall making a fine little carbon arc light/furnace that operated
off 110V AC, back in my foolish youth...

BillW

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@170052 by Mike Singer

picon face
Bob Ammerman wrote:
> DC is used for very high voltage (1 MVolt+!) long
> distance power transmission. For one thing, it
> avoids the skin effect.

Could you, please, estimate the depth of a skin
effect in copper lines at 60Hz AC.

Mike.

(Perhaps losses due to coronal glow at 1 MVolt+ are
greater)

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@171337 by Herbert Graf

flavicon
face
> Bob Ammerman wrote:
> > DC is used for very high voltage (1 MVolt+!) long
> > distance power transmission. For one thing, it
> > avoids the skin effect.
>
> Could you, please, estimate the depth of a skin
> effect in copper lines at 60Hz AC.

       More then enough when you consider the number of amps flowing. Remember,
we're not talking about 22 gauge conductors... TTYL

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@173905 by Peter L. Peres

picon face
>> I don't think any country uses DC for power transmission.
>
>Except for a couple 0.5MV systems, you're right.

DC is used for very long transmission lines. The wavelength at 50Hz is
6000km and if any line segment approaches (even by far) one quarter of
this (1500km) then a significant part of the energy will be radiated into
space. Also dielectric loss in air becomes very high over such distances.
So people who have really long overland line segments use very high DC
voltages. What I was intrigued by was, how does one convert 0.5MV DC
*down* (up is relatively easy) to something reasonable, like 110kV. Are
they using valves ? If they do, are they buried in lead ? (500kV + vacuum
electrons = hard x-rays).  What semiconductors would work at 500kV and
several amps ? (2A at 500kV is 1MW.  - wow). What happens to birds that
sit on the wire ? (corona at 500kV is fierce). What about lightning. The
wires must be really high up. 500kV would jump 0.5 meter gaps w/o corona
but much more with ? Uhh.

Peter

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@174526 by hard Prosser

flavicon
face
And don't forget, long distance transmission lines are ususally a composite
cable with a steel centre and outer aluminium conductors. (to increase the
strength of the cable & allow  a reasonable distance between towers). With
AC, the steel can contribute to additional magnetic losses, in addition to
the resisitive effect.

Richard P




                   Herbert Graf
                   <mailinglist@FA        To:     spamBeGonePICLISTSTOPspamspamEraseMEMITVMA.MIT.EDU
                   RCITE.NET>             cc:
                   Sent by: pic           Subject:     Re: [OT] Saftey issues: AC vs DC
                   microcontroller
                   discussion list
                   <PICLIST@MITVMA
                   .MIT.EDU>


                   28/04/03 09:12
                   Please respond
                   to pic
                   microcontroller
                   discussion list






> Bob Ammerman wrote:
> > DC is used for very high voltage (1 MVolt+!) long
> > distance power transmission. For one thing, it
> > avoids the skin effect.
>
> Could you, please, estimate the depth of a skin
> effect in copper lines at 60Hz AC.

       More then enough when you consider the number of amps flowing.
Remember,
we're not talking about 22 gauge conductors... TTYL

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@175825 by hard Prosser

flavicon
face
In NZ the "DC link was upgraded about 10 years ago from +/- 500kV to
+/-750kV IIRC.
This link runs from the Southern Area of the South Island to the South end
of the North Island  - a distance of maybe 600km (?) including an undersea
section. The link is bi-directional but, due to the population & energy
requirements, is pretty much entirely used in the South - North direction.

Corona Discharge is visible at times - as is a slight "hair raising"
feeling when putting out on one of the local golf courses - with the
transmission line appearing to be far too close overhead! (Could be an
imagined effect however).

Voltage conversion is carried out by solid stae devices (thyristors (?)) at
both ends.

The link also carries fibre optic communication cable - used by the power
transmission people & with additional capacity sold/rented to other users.

All the above subject to correction.

Richard P









>> I don't think any country uses DC for power transmission.
>
>Except for a couple 0.5MV systems, you're right.

DC is used for very long transmission lines. The wavelength at 50Hz is
6000km and if any line segment approaches (even by far) one quarter of
this (1500km) then a significant part of the energy will be radiated into
space. Also dielectric loss in air becomes very high over such distances.
So people who have really long overland line segments use very high DC
voltages. What I was intrigued by was, how does one convert 0.5MV DC
*down* (up is relatively easy) to something reasonable, like 110kV. Are
they using valves ? If they do, are they buried in lead ? (500kV + vacuum
electrons = hard x-rays).  What semiconductors would work at 500kV and
several amps ? (2A at 500kV is 1MW.  - wow). What happens to birds that
sit on the wire ? (corona at 500kV is fierce). What about lightning. The
wires must be really high up. 500kV would jump 0.5 meter gaps w/o corona
but much more with ? Uhh.

Peter

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@181529 by Dave Tweed

face
flavicon
face
Mike Singer <KILLspammsingerspamBeGonespamPOLUOSTROV.NET> wrote:
> Bob Ammerman wrote:
> > DC is used for very high voltage (1 MVolt+!) long
> > distance power transmission. For one thing, it
> > avoids the skin effect.
>
> Could you, please, estimate the depth of a skin
> effect in copper lines at 60Hz AC.

http://www.circuitcellar.com/library/eq/153/3.htm

-- Dave Tweed

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\27@183645 by Herbert Graf

flavicon
face
> Mike Singer <EraseMEmsingerspamEraseMEPOLUOSTROV.NET> wrote:
> > Bob Ammerman wrote:
> > > DC is used for very high voltage (1 MVolt+!) long
> > > distance power transmission. For one thing, it
> > > avoids the skin effect.
> >
> > Could you, please, estimate the depth of a skin
> > effect in copper lines at 60Hz AC.
>
> http://www.circuitcellar.com/library/eq/153/3.htm

       Thanks, I didn't feel like pulling out my E&M text... :) 20mm? Wow, that's
worse then I thought, I thought at least an inch. TTYL

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads

2003\04\28@033739 by hael Rigby-Jones

picon face
{Quote hidden}

The way I read that, a cable 40mm in diameter would suffer no extra losses
through skin effect at 60HZ.  I wouldn't have thought that long distance
transmission lines were much thicker than 40mm?

Mike


=======================================================================
This e-mail is intended for the person it is addressed to only. The
information contained in it may be confidential and/or protected by
law. If you are not the intended recipient of this message, you must
not make any use of this information, or copy or show it to any
person. Please contact us immediately to tell us that you have
received this e-mail, and return the original to us. Any use,
forwarding, printing or copying of this message is strictly prohibited.
No part of this message can be considered a request for goods or
services.
=======================================================================
Any questions about Bookham's E-Mail service should be directed to TakeThisOuTpostmaster.....spamTakeThisOuTbookham.com.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics

2003\04\28@075823 by Alan B. Pearce

face picon face
>> I don't think any country uses DC for power transmission.
>
>Except for a couple 0.5MV systems, you're right.

In New Zealand they have a DC system between the North Island and the South
Island. The DC is then converted to AC using Mercury Vapour Thyratrons IIRC.
I cannot recall just what the maximum power transfer capability is.

This system was necessary to transfer power between the islands as it was
too difficult to synchronise the AC power of both islands through the cables
which do have a (relatively) limited capacity IIRC.

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics


'[OT] Saftey issues: AC vs DC'
2003\06\25@025424 by Brendan Moran
flavicon
face
>AFAIK AC can not be used for very long lines, for instance in Sweden
>between the power generation (in middle and north of the country) and
>the use (mainly in the south).

It is my firm belief that that is inaccurate.  In British Columbia, Canada,
there is a large scale power generation facility called the WAC Bennett Dam
(2.73MVA generating capacity).  The eventual destination of the majority of
this power is the Greater Vancouver area.  This destination is
approximately 770km away from the dam at the closest point.  This power
also runs the length and breadth of Alberta and British Columbia.  On top
of that, due to the California Energy crisis, BC Hydro (the owner of the
WAC Bennett Dam) is selling power to the state of California.  That is 1500
km from the generating station.  It should further be pointed out that the
entire North West power grid (In North America) runs from southern
California to at least southern Yukon, which is a combined distance of 3300km.

To the best of my knowledge, the entirety of that power grid is AC power of
varying voltages (or at least all the power lines I've seen are 3 wires,
and the lines leaving the generator are 3 wire.  If they were going to
convert to DC, I'd expect them to do it at the generating facility rather
than build a separate facility).  There is one exception to that that I
know of, which is an SCR switched DC line out to an island in BC.  That is
a relatively short run and is not along the main power stream, but rather a
branch from it, and there may well be more like it.

So, yes, AC power can go a long way.

--Brendan

--
http://www.piclist.com hint: To leave the PICList
TakeThisOuTpiclist-unsubscribe-requestKILLspamspamspammitvma.mit.edu>

2003\06\25@053521 by Katinka Mills

flavicon
face
{Quote hidden}

I remember reading something about DC being better for long runs (Russia has
the worlds highest DC voltage and longest length DC run).

The reason the grid is AC in most countries is to facilitate tapping off for
cities and towns along the way, if the main run was DC it would cost more as
you would need an inverter at every tap off point.

If I can find the link to the Russian Power line and the reason I will post
it :o)

Regards,

Kat.
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.443 / Virus Database: 248 - Release Date: 10/01/2003

--
http://www.piclist.com hint: To leave the PICList
spamBeGonepiclist-unsubscribe-request@spam@spamspam_OUTmitvma.mit.edu>

2003\06\25@100243 by Stephen Webb

flavicon
face
> >AFAIK AC can not be used for very long lines, for instance in Sweden
> >between the power generation (in middle and north of the country) and
> >the use (mainly in the south).
>
> It is my firm belief that that is inaccurate.  In British Columbia, Canada,

Yes.  Isn't one of the main benefits of AC that it can be easily stepped
up/down -- high voltage for long runs (minimizes the I^2R losses), and low
voltage at the pole to your house...Doing this with DC would be a much
more difficult job, no?

-Steve

--
http://www.piclist.com hint: To leave the PICList
TakeThisOuTpiclist-unsubscribe-requestspamspammitvma.mit.edu>

2003\06\25@115533 by Herbert Graf

flavicon
face
{Quote hidden}

       It depends on the situation. AC power can go as far as you want, the
problem is losses, after a certain distance the losses with AC overweigh the
additional costs of a DC run. There are several long lines in Canada that do
DC. In your case it's possible that there are "taps" along that 1500km
meaning no single stretch of line is long enough to warrant using DC on it.
TTYL

--
http://www.piclist.com hint: To leave the PICList
piclist-unsubscribe-requestEraseMEspammitvma.mit.edu>

2003\06\25@142611 by Chris Loiacono

flavicon
face
sugg...reading the comparative history of Edison (DC) vs. Tesla (AC).
Edison had the early lead until his DC distribution scheme started burning
whole city blocks in NY. Enter Tesla's rotating current generation...or
whatever he called it..
{Quote hidden}

--
http://www.piclist.com hint: To leave the PICList
RemoveMEpiclist-unsubscribe-requestEraseMEspamspam_OUTmitvma.mit.edu>

2003\06\25@180813 by Daniel Serpell

flavicon
face
On Wed, Jun 25, 2003 at 10:01:54AM -0400, Stephen Webb wrote:
> > >AFAIK AC can not be used for very long lines, for instance in Sweden
> > >between the power generation (in middle and north of the country) and
> > >the use (mainly in the south).
> >
> > It is my firm belief that that is inaccurate.  In British Columbia, Canada,
>
> Yes.  Isn't one of the main benefits of AC that it can be easily stepped
> up/down -- high voltage for long runs (minimizes the I^2R losses), and low
> voltage at the pole to your house...Doing this with DC would be a much
> more difficult job, no?

The advantage of DC is no need to syncronize each power source.
Syncronization at long distances is really difficult, and a little
phase shift can cause major power outages.

   Daniel.

--
http://www.piclist.com hint: To leave the PICList
@spam@piclist-unsubscribe-requestRemoveMEspamEraseMEmitvma.mit.edu>

More... (looser matching)
- Last day of these posts
- In 2003 , 2004 only
- Today
- New search...