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Amorphous distribution transformers
Submitted by Anne Rialhe on Tue, 2007-11-13 13:57.
Technology
The reduction in Joule losses during the transport of electricity from power station production to users necessitates the use of high voltage and low amperage. Distribution electricity for domestic users, on the other hand, requires low voltage. Distribution transformers (DT) reduce the voltage of the electricity between the transport and the distribution. Two losses occur in DT: no-load losses, simply due to the fact that the DT is on the electric grid, and load losses, a function of the electric load.
Enhancements
Amorphous transformers use amorphous steel, instead of grain oriented steel. This change allows a significant decrease of losses in DT, resulting in energy savings. They are currently used in the USA and in India but not in the European Union. This situation exists because amorphous transformers are produced for voltages other than that used in Europe. Transformers are a local market, and amorphous DTs are therefore not produced in the EU. Furthermore, electric utilities prefer technologies they have already tested to those, which however promising they may be, are unfamiliar.
Future
The future of efficient and very efficient DT lies partly in a three step change: firstly, choosing the most efficient transformers from existing models (22 TWh savings have been estimated for the European Union), secondly, opting for amorphous transformers, and thirdly, switching to new technologies not yet industrially developed (as supra-conductive transformers).
Distribution transformers, new and old (Photo AERE)
Amorphous distribution transformers
There are a few factors regarding Amorphous transformers that always seems to be overlooked. Yes the technology is there however let's look at some other issues.
Today the annual consumption of electrical steel is in the range of 1.8-2 million ton of grain oriented steel while the production capacity of amorphous metal is roughly 60 000 ton. An amorphous transformer has approximately 50% larger core due to saturation limitations and larger stacking factor. So let's make it easy for us and say the annual production capacity of amorphous steel is equivalent to 40 000 ton of grain oriented steel. Then the maximum width of amorphous metal is 250 mm so it can not be used for power transformers. Let us say that the usage is 1/3 for power and 2/3 for distribution transformer. This would give a usage of 1.2 million ton of grain oriented steel for distribution transformer against a capacity today of 40 000 ton grain oriented steel equivalent. Roughly 3%!
Bigger core also result in more copper being used and more insulation materials like paper and oil. I understand why copper producers support amorphous steel as they then will sell more copper.
Todays manufacturing technologies in Europe is based on stacked core designs. Amorphous steel is 1/10 of the thickness of grain oriented steel and hard as tool steel. This makes it near to impossible to use in stacked designs. The reason it is used in US and Japan is that the technologies used there are wound core designs. The cores are not manufactured inhouse but at the steel suppliers facilities. These two basic designs are so far apart that European manufacturing equipment could not be used. The day amorphous transformers could replace todays technologies on a larger scale we will already have super conducting technology. Then we will also not need transformers.
superconductors at least do not burn well
Dear Jan,
the lack of production capacity is a very poor argument to bring forward against any new technology. It could always be applied against everything. We might just as well turn the tables and say that superconductors have no chance at all because the worldwide production capacity is way too small compared to the world's conductor market. The capacity will grow as demand grows – no sooner than that.
The interest of the copper industry is evident and no secret, although the amorphous metal producers say that recent progress has brought the saturation up to 1.5T or even more, so the difference is dwindling away. But still, the copper people support this technology because they feel obliged to global energy efficiency improvements in general.
The unavailability of big cores is also a very poor argument against building the small ones. Most of the losses occur in small transformers. A bulk supply point or generator transformer has only some 0.02% of core losses, a distribution transformer has 10 times as much. But on the other hand the distribution transformer is too small and the absolute loss is too low to undergo the effort of cooling.
The superconducting transformer is a fairy tale. It will never come, unless someone invents a superconductor that works at room temperature. With an efficiency of 99.75% at full load and 99.80% at half load, there is too little left to save up because the cooling still needs to be fully sustained, be it at full load, part load, no load or during a shorter interruption of the transformer’s operation. Distribution transformers, on the other hand, are too small and the absolute loss is too low to undergo the effort of cooling.
Also note that superconductors can save the copper losses only, not the core losses. Rather, when you use common magnetic steel, its specific resistance will drop and yield a substantial increase in eddy current losses at lower temperatures. So you should cool the winding only and leave the core warm, but still the core will inevitably heat up the adjacent windings and add to the need of cooling.
Although it could have been calculated in advance, Siemens tried it out and built a prototype, but alas, there was no saving at all.
And now please tell me why we don’t need transformers any more when we use superconductors. The latest news is that a 50kV superconducting transmission cable has been devised. I don’t have any appliances for 50kV in my home, and I also don’t want any.
You had better forwarded the argument that a superconducting transformer does not burn so very well as the one filled with tons of oil which went on fire at Krümmel nuclear power plant. This at least would have been true (also see www.ivsupra.de), whenever leaving the question open how relevant this feature is.
amorphous cores
Amorphous v GO
Stefan,Roman,
I work for a GO producer , so I can't pretend to be totally objective but I have to say I agree with Jan ( who I see actually works for a Transformer manufactuer ! ) From a "green" perspective it would be great if the world could have all new transformers with significantly reduced losses , but where will all this amorphous material come from? if you're right and that the market will make it happen Hitachi would be planning to increase it's production capacity ten- twenty fold not less than twice.(or we'd see a hugh rush of new manufacturers ) But in fact what we're seeing at the moment is a rise in demand for GO.
Have you guys any knowledge of flat stacked amorphous transformers ( power core came and went) ? again unless things change radically and transformer manufacturers move entirely to wound cores there will always be a practical limit to the size of transformers that can be built with amorphous material.
It would be good for you guys to get the views of Transformer manufacturers to add some balance to your comments/reports at the moment I feel you're not quite reflecting the realities of what's practical.
How did the workshop on Transformers go , will you be making the presentations available ?
Amorphous Metal production flow
www.zhixindianqi.com.cn/en/ci3.aspx
www.metglas.jp/eng/f-amorphous.html
I hope this amorphous production chart will help