Electric Transformer

[sudsmaster]

Um, what is meant by "raw power"?

Do you mean extremely (by household standards) high voltage and amperage?

I suppose sufficient voltage running down the wires to the home might cause arcing over in the breaker box... But then I'd also expect it to arc on the way down to the breaker box... Something seems non standard about the way those homes were wired... perhaps not to code or code not followed?

It looks however that the guy in the bucket survived. The arcing on the high tension wires seems to have gone on waaaay too long.

 

[sudsmaster]

Apparently the high tension power line broke and contacted the ground wire. I guess the ground wire also must have had a one-way route to the block of homes. Since ground wires are not normally protected by breakers on the homes, that current would have gone through the homes' ground location seeking the path of least resistance. Apparently the homes had interconnected the service ground to the homes' gutters and plumbing, which caused these to heat up and start the blazes. Possibly some of that smoke is really steam from overheated water in the plumbing (some homes built on slabs have the plumbing running through the attics instead of under the slabs). At least this is what I gather from looking at few web sites that talk about the incident.

I do remember what an electronics instructor told our class back in 1984: "Never trust the ground wire coming in from the utility"...

Which reminds me... I need to install another ground rod at the electrical service entrance...

 

[alr2903]

mielabor, Togs and i are speaking of runs of electric cable in the urban jungle, these large grates are present in the sidewalk, where i would guess several tranformers and lines tie together, kind of like one kitchen table sized grate in an entire block of concrete sidewalk, so to speak. alr2903

 

[toggleswitch2]

110v or 220 at end use is of no importance, in this case.

More and more use of air-conditioning in summer has lead to catastrophic loss of power and burnt cables.

Air-conditioners were over $250 in the 1970's and are now $80 to $100 (Thank you China). Everyone including the poorest of the poor now has one in this city.

My apartment building was buit in 1945 and has only 30a 110v service (say 3,300w)per apartment. To make it worse, I think 8 apartments have only 100a 110/220v main service coming in. With 4 apts per 110v leg, there is only 100a to split between 4 units. (4 x 30= 120a demand)

We are so far behind in so may ways it is scary!

 

[tolivac]

Grates in the city-When I was in Wash DC-these grates were common-esp in front of buildings-and the buildings power feeder transformer was under the grate.Hate to be the utility tech who have to work on the equipment-its covered with cigarette butts,dried spit and food remains-not to mention dead mice and rats,snakes,etc.
And yes I have seen people sitting on power transformers in front of buildings,houses while waiting for their bus-if only they knew what they were sitting on!-sometimes these let go!!I would want to pick something else as a seat.
At my workplace some electric renovations are underway-all of our MV and LV breaker panels are being replaced-it has to be timed to keep airtime loss at a min.And the contractors have gotten rid of some older transformers no longer used-and they held PCB dielectric cooling fluid.From the substation out here-the 4160V cables run thru a water filled area that is always wet-high water table here-so the cables have to be specially waterproofed-imagine if one or more failed-that water would be boiling!!I have seen other buildings where their power cables go thru water filled basements and conduits.SCARY!!!

 

[sudsmaster]

Not just debris...

One of the sites I visited mentions that underground cabling and transformers in the Northeast has a special challenge - the salt used on roads in the winters there gets into the chambers and corrodes the wiring, which then can lead to wiring/transformer failure/explosion.

 

[circlew]

Yikes! That would be very scary to see something like that. The closest thing to that around here was when the power co. (municipal owned) replaced a 120/240 volt 1ph transformer with a 480 volt by mistake. They had bought some used units, and they claimed it was mis-marked, but I also heard from others they just picked up the wrong one. This transformer served 5 houses. Due to the higher voltage going in to the buildings, it burned out the motors in the people's refrigerators and some other appliances, and ruined their TVs, VCRs, and other electronics. The power co. didn't want to pay, so the homeowner's insurance had to.
In another instance, a vehicle hit a power pole a couple miles from here. A high voltage line fell onto a lower voltage line, causing a momentary surge to the area served by the lower voltage line. This cause some electronic items to be ruined. The main substation breakers did trip, causing a widespread power outage - knocking out power to all of Goshen, Blanchester and Newtonsville.

 

[tomturbomatic]

Transformer failure is a major threat to the world's electrical grid. Transformers are not mass-produced items. If a plasma discharge from a solar storm were to breach Earth's magnetosphere, transformers would be overloaded and destroyed. The electrical grid could be down for months and even years. We would be shoved back in time more than a hundred years without the resources of those times. Even natural gas service would be disrupted without electricity to power the pumps, likewise water and sewer systems.

http://www.examiner.com/x-2383-Hono...grid-failure-from-2012-solar-storms-avoidable

 

[tolivac]

WHAT Tran sformers not mass produced-yes they are!!!That is a big reason there is so many of them.Visit a transformer factory sometime!even the larger substation transformers are mass produced-and factories produce custom ones like for our facility-IE as a replacement for one of our transmitters a rectifier transformer-primary 4160V 3p sec-two 10Kv 3Ph secondaries for 6 phase rectifier to get 30Kv DC at up to 20A.Distribution transformers are the most mass produced(pole pigs and URD transformer) that feed into your home or business.Most common 13.8-7.4Kv primary-240-120V secondaries for homes-13.8Kv primary-208-120V secondary in a 3 ph bank-pole pig-and another pole pig-ground mount 13.8Kv primary-480-277V secondary pole pig or ground mount.I had to oversee and specify a 3 phase bank of transformers for a 50Kw AM radio station transmitter site-3 pole pigs 100Kva each-13.8Kv primary voltage 480-277V secondary.Lower power station use 208-120V or 230V transmformer banks.or one ground mount 3 ph transmformer-these are becoming more common.
The 480V screwup by that power company-a 480V transformer in a residentual feeder--you bet your A?? they would be responsible-negigence on their part-anyone got hurt?The homeowners should hire a lawyer and sue-would be an open-shut case!!If the power co tech can't read a nameplate on a transformer--they aren't qualified for the job!!A transformer that has its plate missing should not be used.A turn ratio tester could determine its specs though.none the less unmarked transformers shouldn't be used.That power co or the contractor that did the work would indeed be reponsible for any injuires and damages.

 

[tolivac]

Transformers are pretty interesting electrical-electronic devices-they do the function without any moving parts or vacuum tubes or semiconductors-just two or more coils of wire wound on a soft iron core.(soft iron has low periability-does not retain a magnetic charge)and the transformer can do its job for years or even decades with surpizingly little care or mainteanance!

 

[tomturbomatic]

If the majority of transformers in the world or even in a few countries were damaged or destroyed by an electromagnetic pulse, it would take a very long time to build enough of them to bring the grid back up. And, with our depleted manufacturing capacity, if China needed to replace their transformers, don't think that they would be willing to sell transformers to us.

Mielabor, if I might clarify something, the underground cables are under the streets in tunnels or buried under the earth in tubes. The grates are over the vaults where the transformers are located to allow air circulation to dissipate heat.

 

[mielabor]

Underground cables...

Clearly a different layout there in the USA. Our cables are usually not in tunnels or tubes (with exception of fiber optic cables) and transformers are above ground, either in existing buildings or in structures specifically built to house them. Probably because the ground can be wet: in some places the water table is only a few decimeters below the surface. The vertical yellow tubes in the picture are connected to a pump for lowering the water level to facilitate working in the ground.

 

[mielabor]

And this is what one usually sees when they are working on the cables or sewer tubes...

 

[tolivac]

Visit your electric companies salvage yard-lots of transformers there!go to a transformer factory-lots more there too-Don't think shortage of transformers is going to be a problem.And most transformers are adequietly protected from EMP and lightening and surges-The surge protector is the insulator like device that is on most pole type transformers-and in the case of ground mount ones-and the device is easily replaced.When it faults-usually blows the transformer primary fuse.I wouldn't worry about mass utility co mass transformer failers.The lines themselves are more likely to have problems before the transformers.For the US many of our utility co transformers are built or repaired in the US-GE does have a distribution transformer factory in Mexico-the plant makes pole type and URD mount transfromers there.Pensylvania Transformer Technologies has a plant near Goldsboro,NC that made our special order transformer-been by the place-they build and repair substation transformers and several in their yard waiting for sale or delivory to customers.GE,Square D,Westinghouse-Seimens,Brown Boveri,have factories in the US and worldwide.