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Estádio Zezinho Magalhães, Jaú, SP - Brasil - Copinha 2025 - Fluminense x São Paulo
FOTO: LEONARDO BRASIL/ FLUMINENSE FC
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(If anyone can add to, or correct any of the information below, please post such addition or correction as a comment and I will update this article. -- Thanks)
These links might be interesting. They are a two part Television program called Success Story that show Westinghouse transformers being manufactured at the Westinghouse Sunnyvale Plant in Sunnyvale, CA, in the 1950's:
www.youtube.com/watch?v=3eD_i94WFsk
www.youtube.com/watch?v=UOE0DMNfbog
I have studiedd the history of electrification, as I find it very interesting.
After Edison's DC system proved to not be practical, and once the plan for electrifying the country was worked out by engineers (probably working at General Electric and Westinghouse), it was decided the distribution voltage was to be standardized at 2400 or 4800 volts, phase to phase, although there were many early grids operating at oddball voltages in the early days. It was to be a three phase 3-wire (delta) system, with the transformers connected phase to phase. A single phase distribution line was simply any two wires taped from the three phase system.
Previously, Edison had electrified parts of New York City with his DC system, and William Stanley, Jr., the inventor of the practical transformer had electrified (for lighting only) Great Barrington, MA, in 1886. Using transformers that he designed and built, he stepped up the generator's output of 500 volts to a distribution voltage of 3000 volts, with his transformers at the point of use stepping this voltage down to 100 volts.
Lots of interesting information about this can be found at:
edisontechcenter.org/GreatBarrington.html
Part of the problem of adopting AC was that early on there was no practical AC electric motor. DC motors were much simpler and until an AC motor was developed AC would not be accepted. And Edison's system in NYC provided power for both lighting and motors. In fact, ConEd continued to supply DC power to older buildings that had DC motors -- mostly for elevators -- until recently. After the ConEd DC generators were gone, they still used rotary converters, and later rectifiers, to provide DC power to some customers who needed it up to just a few years ago.
But by the late 1890's AC electric motors became available and household electrification using AC in the US with distribution systems operating at 2400 volts (delta connected primaries) began around 1905 in urban areas.
Actually, back at that time, the voltage was 2200 volts, which resulted in service to the customer side of the transformer of 110/220 volts in the United States. Over the years, this has been gradually increased, and is now a nominal 120/240 volts for residential and small commercial/industrial customers. For all voltages in this article, I use the modern voltage. In the original system, using these voltages allowed for a very convenient ratio of 10:1 (20:1 for 4800 volt transformers) for the windings of the transformers.
Most early three phase distribution systems were connected in delta on the primaries of the distribution transformers. This is where the three windings are connected together with three connections, and if you draw a schematic it looks like the Greek letter "delta". Later, as systems were upgraded, many if not most systems were connected so that a schematic looks like the Roman letter "Y", with the common point of the three windings usually grounded. This is usually spelled out as "wye".
Also it is helpful to understand the mathematical relationship between transformers connected delta or wye. In a wye connected three phase AC system, due to the 120 degree difference in phase between phases, the phase to phase voltage is 1.73 times the phase to neutral voltage, and the phase to neutral voltage is the phase to phase voltage divided by 1.73. 1.73 is the square root of three. It requires a bit of trigonometry to figure out why the factor is 1.73.
At any rate, 2400 volts was high enough to be able to use small size conductors on the distribution lines, and originally, electrification was just in the urban areas of cities and towns where the primary distribution lines were not that long, and loads were just lighting and very few appliances.
Later, as loads increased, most of these systems were upgraded to 4160 volts phase to phase (wye connected primaries), which made the phase to neutral voltage 2400 volts. A 4th wire was added, the neutral, and the 2400 volt transformers were reconnected phase to neutral. Almost all 2400 volt delta systems have been upgraded to 2400/4160Y (a few remain 2400 volt delta), and many old sections of urban areas that were originally electrified still use systems operating at these voltages. This is where you will see a lot of really old transformers, some dating back to the early days, and some really old ones with cast iron tanks.
Interestingly, while the distribution voltage in Manhattan is 100% 7960/13,800Y, many areas of Queens, Brooklyn, The Bronx, Westchester County, etc., still use 2400/4160Y according to Con Ed's web site.
But as electrification spread into the suburbs and rural areas, distribution voltages became necessarily higher. These increases in voltage allowed the currents on the distribution lines to remain low enough that small conductors could be used on the distribution lines and losses were not too high as the amount of power required increased.
Here is the upgrade path that was taken, as upgrades were required, from the original 2400 volt delta wired system:
Original system -- 2400 volt delta only using 2400 volt transformers connected phase to phase
Upgraded to 2400/4160Y using old 2400 volt transformers connected phase to neutral and new 4160 transformers connected phase to phase -- a lot of urban areas still operate at this voltage, including areas around NYC as mentioned above.
[Correction: 4160 volt transformers were never used, as pointed out in the comments below by NDLineGeek. Rather, all transformers on this system are 2400 volt connected phase to neutral.]
In some urban/suburban/moderately populated close-in rural areas that were electrified (for the first time--not upgraded) a bit later, say beginning in the 1910's, other voltages were sometimes chosen, because they did not have existing transformers to re-deploy.
A very common original distribution voltage for systems serving these types of areas was 4800 volts delta. This voltage was chosen for its own merits, not to allow for older transformers to continue to be used. Since these systems were built some years after the original 2,400 volt delta systems, the technology to use higher voltages had evolved, and this was a better choice for systems that covered towns that were a bit more spread out, or had more thickly populated near-by rural areas.
Areas like this were electrified much sooner than the spread-out rural areas of the mid-west, south, and far west. And since this was all original build, there were no old transformers to have to re-use. Originally, the 4800 volt systems were delta, and the transformers were connected phase to phase. The upgrade path for these systems was to upgrade to 4-wire wye, and the phase to phase voltage was 1.73 times 4800, or about 8320, which allowed the old 4800 volt transformers on these systems to be connected phase to neutral when they were upgraded. Indeed, most of these systems have been upgraded to 4800/8320Y, but I have read that a few remain operating at 4800 volts delta, including quite a few systems in CT that remain 4800 volt delta systems. Other areas of Connecticut operate with 4800/8320Y, with most transformers connected phase to neutral at 4800 volts. In these areas you will see some very old Westinghouse transformers, most of which are from the 10's, 20's, and 30's. Some have cast iron tanks; these are the oldest transformers still in use. This voltage works well in places like Connecticut because the towns, and their surrounding close-in rural areas, are not spread out too much for this voltage.
Another voltage used for first-time build for truly rural electrification was 7200 volts, wired delta, using 7200 volt transformers connected phase to phase. In the early days, this voltage was 6600 volts, which was stepped down to 110/220 with transformers that used a winding ratio of 30:1. Today, these same 30:1 transformers deliver 120/240 volts with 7200 volts on their primaries. These systems were originally built at this voltage beginning in the mid 1930's in delta configuration as a result of Roosevelt's enactment of the Rural Electrification Administration in 1935. Since these were all new systems there was no concern for using old transformers, but 6600 (now 7200) volts was chosen.
Over time, most of these systems have been upgraded to 7200/12470Y which has allowed for the continued use of 7200 volt transformers, but allowed for a less expensive transformer to be built once the systems were upgraded. The original 7200 volt transformers for the delta system had to have two high voltage connections going into the primary of the transformer, whereas the wye connection only required one high voltage bushing, as the other connection is to the neutral, which is grounded. On these systems, you will see a mixture of transformers, some with two HV bushings, and some with just one bushing. Most of these systems continue to operate at 7200/12470Y, and is a very common standard.
Note that for some of the upgrades, the original phase to phase voltage was multiplied by 1.73 so the phase to neutral voltage for the upgrade remained the same as the original phase to phase voltage.
Besides the standards discussed above, some other distribution voltages you will see used to-day are:
12000 (delta)
7620/13200Y
7960/13800Y
13200/23000Y
13800/24000Y
14400/24900Y
19920/34500Y
The history of why these voltages were chosen is a bit murky, at least to me. Here are some thoughts:
12000 volts delta is an old transmission standard from long ago, and while distribution systems using 12000 volt delta systems are not very common some were built for systems that operate over wide spread rural areas out west. Of course, since these were built using a three wire delta configuration, this required 12000 volt transformers.
7620/13200Y volts is a distribution voltage that is in common use. This is the voltage that is used in both Greenwich, CT, where I used to live, and Boca Raton, FL, where I now live. Also, since 23000 volt wye systems have 13,200 volts phase to natural, perhaps 7620/13200Y volts became convenient to use as a sort of downgrade when old 23000 volt transmission lines were no longer adequate for transmission and some were downgraded to distribution and converted to wye service. Just a thought, I don't know for sure.
7960/13800Y may have evolved from the fact that 13800 (delta) was an old transmission specification which was changed to wye and then used for distribution. While this article is primarily about distribution voltages and transformers, another interesting tidbit is that 27600 volt delta sub transmission is twice the old 13800 volt delta transmission voltage. As loads increased, it probably made sense to double the voltage, which would allow twice the power using the same size conductors, and this may be why 27600 delta is a standard sub transmission voltage to-day.
13200/23000Y, 13800/24000Y, 14400/24900Y, and 19920/34500 became distribution voltages for the same reason: old delta distribution voltages (the higher voltage) were changed over to wye and adapted for distribution. However, these higher voltages are not as common as the lower voltages for distribution.
For all these various distribution voltages, transformers are rated as follows:
HIGH VOLTAGE CONNECTIONS:
Phase to Phase Only:
These transformers HV bushings and coil can only withstand a limited voltage from the system ground, and must be connected phase to phase. Their rating will show only the coil voltage, as in 2400. 4800, 7200, etc.
Phase to Phase, or Phase to Neutral:
These transformers use fully insulated coils, and two HV bushings. Their rating will look like 7200/12470Y, where the coil voltage is 7200. Such a transformer could be connected phase to phase on a 7200 volt delta system, or phase to neutral on a 12470 wye system.
Phase to Neutral only (usually only have one HV bushing):
These use “graded” insulation, where there is less insulation at the end of the winding closest to ground. It will have a rating such as 4160GrdY/2400, or 13200GrdY/7620. This transformer will have a 2400 or 7620 volt coil, but one end of the coil must be connected to the neutral of a wye system as the insulation on the end of the coil is not capable of supporting a voltage that is the rated coil's voltage to ground.
LOW VOLTAGE CONNECTIONS:
120/240 V means the secondary can supply a load at either 120 or 240 volts as long as neither 120 volt coil section is overloaded
Transformers that can be internally reconnected from two wire to three wire service are designated 120/240 or 240/480 V (the smaller value first)
Transformers that cannot be reconnected are designated 240/120 or 480/240 V
It is interesting to me that many of the common voltages used to-day, and the voltages of early systems, used multiples of 10 for the distribution transformer ratio. Here are the ratios showing the present day primary voltages:
10:1 -- 2400 volts
20:1 -- 4800 volts
30:1 -- 7200 volts
50:1 -- 12000 volts
60:1 -- 14400 volts
Transformers with these ratios will deliver 240 volts on their secondaries (and 120 volts on either side of the secondary center tap) and can be connected phase to phase on delta systems operating at these voltages, or phase to neutral on wye systems operating at these voltages.
The ratios (for 240/120 volts on secondary) for other primary voltages are:
31.75:1 -- 7620
33.167:1 -- 7960
55:1 -- 13200
57.5:1 -- 13800
83:1 -- 19920 volts
Please add your thoughts, corrections, etc., to comments.
Thanks,
Rick
Coal Distribution branded Class 37/0 37223 waits to depart with Speedlink Coal Network [SCN] Train 6B07, the 09:00 Gwaun Cae Gurwen [GCG] to East Usk Yard.
All images on this site are exclusive property and may not be copied, downloaded, reproduced, transmitted, manipulated or used in any way without expressed written permission of the photographer. All rights reserved – Copyright Don Gatehouse
Family: Buprestidae
Size: 14.3 mm (7.0 to 15.0 mm)
Distribution: South Europe, Southern Central Europe
Biology: Development under the bark of dead oaks
Location: Corsica, Aleria
leg.det. U.Schmidt, 26.V.1973
Photo: U.Schmidt, 2018
Shorebirds of Ireland, Freshwater Birds of Ireland and The Birds of Ireland: A Field Guide with Jim Wilson.
www.markcarmodyphotography.com
The Common Tern (Sterna hirundo) is a seabird of the tern family Sternidae. This bird has a circumpolar distribution breeding in temperate and sub-Arctic regions of Europe, Asia and east and central North America. It is strongly migratory, wintering in coastal tropical and subtropical regions. It is sometimes known as the sea swallow. The term "Commic Tern" refers to birds which are not seen well enough to positively determined if they are Common or Arctic Terns.
Its thin, sharp bill is red with a dark tip. Its longish legs are also red. Its upperwings show a dark primary wedge, unlike the Arctic Tern, in which they are uniformly grey. Its long tail extends only to the wingtips on the standing bird, unlike Arctic and Roseate Terns, which extend past the wingtips. It is not as pale as the Roseate Tern and has longer wings. (wikipedia)
The great black-backed gull (Larus marinus) is the largest gull in the world. It is 64–79 cm (25–31 in) long with a 1.5–1.7 m (4 ft 11 in – 5 ft 7 in) wingspan and a body weight of 0.75–2.3 kg. The adult great black-backed gull has a white head, neck and underparts, dark grey wings and back, pink legs and yellow bill.
Great black-backed gulls are opportunistic feeders, apex predators, and are very curious. Unlike most other Larus gulls, they are highly predatory and frequently hunt and kill any prey smaller than themselves, behaving more like a raptor than a typical larid gull. They get much of their dietary energy from scavenging, with refuse, most provided directly by humans, locally constituting more than half of their diet. (wikipedia)
The Great-black backed Gull is resident along all Irish coasts. They are a threat to all nesting seabirds along the Irish coastline during the breeding season. This adult Common Tern was letting the Great black-backed Gull know that it was not welcome at all! The Tern was nesting quite close by. Taken in Broadmeadows estuary, Dublin.
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Family: Carabidae
Size: 6.9 mm (6.0 to 8.0 mm)
Distribution: Japan, Burma, the Philippines, Laos, Taiwan, Borneo, Java, Ceylon, India, northern America (Forida)
Location: Thailand, Prov. Phang Nga, Khao Lak, Similana Resort
leg. U.Schmidt, 14.XI.2007; det. M.Baehr, 2008
Photo: U.Schmidt, 2021