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#146694 - 03/21/07 05:34 AM AC/DC standards war  
Kenbo  Offline
Member
Joined: Apr 2006
Posts: 233
Scotland
Just read this book AC/DC The savage tale of the first standards war

I never new much about the history of our trade but this book has made me think.
It set out the war between Edison and Westinghouse as to which system was the best AC or DC. It shows how nasty and calculating people can be be when trying to further thier own ends. It deals whith what was happening to big buisness electrical supply in America in the 1880s. and finnishes with some intersting facts about today. Just enough facts to make you go and seek out more information.

Anyone advise me about some good reading about how the European industry evolved?

Kenny


der Großvater

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#146695 - 03/22/07 03:21 AM Re: AC/DC standards war  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,217
SI,New Zealand
Kenny,
"Our trade", has had some pretty shaky beginnings.
DC was OK until it had to be distributed over a wide area.
We've all heard the stories of the Edison-Westinghouse spat in the US over AC vs DC distribution, some animals lost thier lives cruelly in the experiments.
AC seems to be the best option so far with the use of transformers.
But you also look at other trades, such as plumbing, they started off in much the same way, I mean open drains and sewers or the pot out the window.
Thank the Lord we've moved on from there!. laugh


Let's face it, these days if you're not young, you're old - Red Green grin

#146696 - 03/22/07 08:30 AM Re: AC/DC standards war  
Kenbo  Offline
Member
Joined: Apr 2006
Posts: 233
Scotland
Mike
I appreciate that everyone has to start learning somewhere and in today's society it seams taboo to deliberately electrocute an elephant, a horse, and lots of dogs "in the name of science" I personally find any kind of animal experiments deplorable and unnecessary.

I am not a transmission man so I found it interesting when in the closing chapter of the book it says that DC is used when transmitting between countries with different frequencies of supply. I could not understand how this could work until.
After a bit of surfing I discovered that it makes sense to convert from one frequency to dc then convert again into the new required frequency. Simple

What I could not find out is why AC cables buried in the ground have a high capacitance effect.
I thought that with the 3 phases close together the magnetic effect would cancel each other out?

It was interesting to find out that HVDC is transmitted in New Zealand between North and South Island. This system has been operating since 1965

Kenny


der Großvater

#146697 - 03/22/07 11:43 AM Re: AC/DC standards war  
mikesh  Offline
Member
Joined: Jun 2006
Posts: 613
Victoria, BC, Canada
One of the HV cables feeding Vancouver Island is 500kv DC. The cables can be seen at the Tsawassen ferry terminal. At the time it was installed DC cable technology was better for the undersea feed. They still use vacuum tube rectifiers too.


#146698 - 03/22/07 03:42 PM Re: AC/DC standards war  
RODALCO  Offline
Member
Joined: Dec 2005
Posts: 854
Titirangi, Akld, New Zealand
Kenbo.

Usually the 3 cables underground are armoured and screened hence the extra capacitance.

This also applies to 3 core XLPE cables. these still have a screen around them and additional armour.


The product of rotation, excitation and flux produces electricty.

#160731 - 03/25/07 08:21 AM Re: AC/DC standards war [Re: RODALCO]  
Texas_Ranger  Offline
Member
Joined: Dec 2001
Posts: 2,400
Vienna, Austria
Only tube rectifiers? wink
Austria exclusively(!) uses rotating inverters to create 16.7 Hz power for the railways to this day! Switzerland seems to be the only country to use solid state inverters yet.


#160732 - 03/25/07 08:42 AM Re: AC/DC standards war [Re: Texas_Ranger]  
djk  Offline
Member
Joined: Dec 2002
Posts: 1,237
Ireland
Here are the technical details of the NIE (Northern Ireland Electricity) to SP (Scottish Power) Interconnector. It ties Northern Ireland into the UK grid using a DC subsea cable:

The interconnection between NIE and SP is carried out using direct current(DC). There are two circuits connecting the two power systems and these are submarine cables approximately XX miles in length.

The cables operate at 250kV DC as two monopolar HVDC transmission systems rated at 250MW per pole, thus providing 500MW transfer capability. The HVDC converter stations are located at Ballycronan More (on Islandmagee in Northern Ireland) and at Auchencrosh (near Ballintrae in Scotland). These converter stations convert the electricity from AC to DC for transmission along the cable and then back to AC again. Power can flow in either direction.

There are two unique features to the equipment involved:-

i) The converter stations are the first in the world designed to use light triggered thyristors(LTT technology). With this technology the thyristors are not triggered by an electrical signal but by a pulse of light – this should make the process more reliable.
ii) The submarine cable design is also a world wide first in HVDC technology as the cables used have a coaxial construction i.e. a metallic ‘return’ conductor is provided as part of one cable.

The link is currently contracted to provide 125MW of power to NI as replacement for NI generation. The rest of the available link capacity (275MW) has been auctioned to energy traders in Ireland.

There are 2 larger interconnectors scheduled to go ahead fairly soon linking the Republic of Ireland to Wales.

"The East-West Interconnector Project"

The exact capacity of the system is yet to be revealed as it's still in the final stages of planning.
total cable length 130km. Also HVDC.

Last edited by djk; 03/25/07 08:43 AM.

#160733 - 03/25/07 08:49 AM Re: AC/DC standards war [Re: djk]  
djk  Offline
Member
Joined: Dec 2002
Posts: 1,237
Ireland
East West Interconnector ONE (Actually longer than on the data I was looking at)


Connection point Ireland Arklow substation
Connection point Wales Pentir substation
Ownership Imera Power
Start of project Summer, 2007
Start of land cable installation Beginning in 2008
Start of submarine cable laying Late summer 2008
In-service (commercial operation) Spring 2009
Transmission technology HVDC Light® by ABB
Transmitted power 350 MW
DC voltage +/- 150 kV
Cable length Total 270 kilometers cables, (2 times 135km)
Maximum water depth 150 m
AC voltage Arklow 220 kV
AC voltage Pentir 400 kV
Features submarine cable Extruded polymer insulated cableConductor 1000 mm2 cupper
Steel armouring Diameter 96 mm
Weight 27 kg/m
HVDC Light® converter stations
Convert alternating current (AC) to direct current (DC) and on the other side DC to AC.
Power direction Power can be transmitted in either direction

Eastwest 2 is larger.

Proposed to be 500MW running from Wexford (southeastern Ireland) to Pembroke in Wales.

Last edited by djk; 03/25/07 08:51 AM.

#160739 - 03/25/07 10:15 AM Re: AC/DC standards war [Re: Kenbo]  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Originally Posted by Kenbo
I appreciate that everyone has to start learning somewhere and in today's society it seams taboo to deliberately electrocute an elephant, a horse, and lots of dogs "in the name of science" I personally find any kind of animal experiments deplorable and unnecessary.


Sentiments I share wholeheartedly. While Edison was undoubtedly a great man in many respects, this is one aspect of his experimentation which I cannot forgive.



#160856 - 03/27/07 04:20 AM Re: AC/DC standards war [Re: Kenbo]  
Trumpy  Offline


Member
Joined: Jul 2002
Posts: 8,217
SI,New Zealand
Originally Posted by Kenbo
Mike,
It was interesting to find out that HVDC is transmitted in New Zealand between North and South Island. This system has been operating since 1965
Kenny


Yes it has mate.
And I would certainly recommend anyone travelling to the South Island here to take a tour of the Benmore Power Station, this is where the AC supply is rectified into DC before being sent north over the DC Link.
They still have tours there I think and it's pretty cool (in a rather unsettling way) to hear the 50Hz hum from the rectifier station and also the huge volume of water that pours down the spill-way to the right of the main power-house, during the winter time.


Let's face it, these days if you're not young, you're old - Red Green grin

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