Whats a transformer made of?

http://photos.nerail.org/showpic/?20060 ... 545120.jpg

Transformers aren't particularly large in size, yet they always get delivered on double trucked rail cars. Why are they so heavy? I know its kind of almost off topic but I'm really curious.

Transformers are two sets of wires wrapped around two iron cores. The amount of windings on each half determines the output voltage. When you are talking about large amounts of voltage and current, you are talking about a lot of wire and iron. And I don't know if they ship them that way, but larger transformers are full of oil, adding even more weight.

Interesting

What are transformers?
(robots, in disguise...... )

The depressed center also allows the tall loads to pass under most bridges.

The oil is added at the site. Transformer oil [mineral oil] is moisture free and is used for cooling.

After lightning strikes, the utility withdraws the oil and circulates it thru a filter machine capable of restoring the di-electric properties.

We made a lot of $$$ spotting empty tankers at the sub station. They filled them w/ the oil while they repaired the damage from the lightning & then pumped it thru the processing machine and back into the transformer.

I had the experience of spending (4) hours waiting on lab work at the shipping point of the transformer oil. The customer then withdrew a quart and placed it in a beaker inserted a pair of electrodes and turned up the current till a sparked passed between them. As long as it was higher than their spec, the oil as good.

A side issue, but perhaps of interest: For some years, the transformer coolant of choice was PCBs (polychlorinated biphenyls). They were non-flamable, resistant to degradation and had desirable properties like viscosity, dielectric coeffeicient and thermal conductivity. Ideal for the use, except they turned out to be an environmental disaster!

alchemist wrote:A side issue, but perhaps of interest: For some years, the transformer coolant of choice was PCBs (polychlorinated biphenyls). They were non-flamable, resistant to degradation and had desirable properties like viscosity, dielectric coeffeicient and thermal conductivity. Ideal for the use, except they turned out to be an environmental disaster!

The GG1's had PCB's!

alchemist wrote:A side issue, but perhaps of interest: For some years, the transformer coolant of choice was PCBs (polychlorinated biphenyls). They were non-flamable, resistant to degradation and had desirable properties like viscosity, dielectric coeffeicient and thermal conductivity. Ideal for the use, except they turned out to be an environmental disaster!

My college, SUNY New Paltz, had a mini-PCB disaster back in 1991.
I was a student there at the time, but was home on Christmas break..(as were most of the students)

My dorm, Gage hall, was one of the dorms that filled with PCB-laden oil smoke..
I lived in Gage hall for one more semester, immediately after the incident.
no personal signs of contamination yet..time will tell.


the "official" opinion:
http://www.newpaltz.edu/healthcenter/pcbupdate.html

the environmental activist opinion:
http://www.planetwaves.net/NewPaltz.Home.html

the truth is probably somewhere inbetween.

Scot

Hi All,

Transformers simply change one AC voltage to another. The size of the unit only tells you how much power it is capable of handling. The frequency of the line voltage has quite a bit to do with it. The higher the frequency of the power, the smaller and lighter the transformer can be. This is obvious on airplanes where weight is a major consideration. Line frequency is generally in the kilocycle, kilohertz range, not 60 cycles or hertz as for normal house etc. power.

l008com wrote:http://photos.nerail.org/showpic/?20060 ... 545120.jpg

Transformers aren't particularly large in size, yet they always get delivered on double trucked rail cars. Why are they so heavy? I know its kind of almost off topic but I'm really curious.

Transformers contain lots of copper windings with a very heavy laminated steel core, not to mention the tap changer, steel tank and control cabinets. One thing that was not mentioned is the transformer insulation. The insulation is made of special paper and is quite heavy. All transformers are shipped filled with an inert gas at pressure, usually nitrogen to keep moisture out. Also, transformers have lots of steel and wood bracing inside. Although transformers are shipped "dry" they still have some oil in them because when they are manufactured they are filled with oil for testing and then drained.
Some units are so large that they are shipped by Schnable Car. A Schnable is quite a sight to see. It is a very large car that can be split in two and then bolted to the load, sort of a transformer sandwich. When the load is delivered, the transformer is slid sideways and the car is bolted back together for it's return home.
One not so well known factoid is there is always a "hump meter" placed somewhere on the side of the unit to measure bangs and jolts enroute. This would help in insurance and repair claims. When the transformer arrives at the railyard, someone goes inside to see if there is any damage. This is why you will always see a "Do Not Hump" sign on the flat car. With the transformer shipment there is usually lots of other stuff like radiators, crates and other large supports for the unit. Sometimes this stuff gets shipped by truck because it is smaller than the unit itself.
Hope this clears some of the mystery to the transformer question.
Jerry Kelley

Cooper now sells a coolant that's soybean oil with BHT in it (yes, the same BHT in Corn Flakes). Highest flash point of any oil out there, it sucks moisture out of the paper. They've had it for a few years.

The stuff's so harmless, you could cook french fries in it, theoretically. NJT uses it in a few places, and their guys LOVE the stuff. Getting hot oil on you or slipping and falling on a spill are basically the biggest concerns with it.

About 1/2 of the volume is taken up by the steel core and the copper in the windings, both weigh 500# per cubic foot. So when you see a large 10’x10’x16’ transformer tank you are looking at a 200 ton block of metal, won’t go in a box car.

Bill

[quote="Nasadowsk"]Cooper now sells a coolant that's soybean oil with BHT in it (yes, the same BHT in Corn Flakes). Highest flash point of any oil out there, it sucks moisture out of the paper. They've had it for a few years.

Hello:
While we are on the subject of dry oil, I guess I should explain the process of trainsformer filling.
Usually, a large transformer is shipped with dry nitrogen gas but when somebody finally gets to go inside the gas is purged with dry air.
After all the work is done inside, inspections, bushing instalation, conservator, and pumps etc. The main tank is placed under a near perfect vacuum. Water, (moisture) evaporates at very low temperatures under a vacuum so most if not all of the moisture will be removed after 24 hrs.
of "pulling" the vacuum.
Enter the oil tankers full of dry oil.
The oil is then pumped through a truck that has a boiler that the oil runs through to heat it up. Then the oil splashes through a vacuume chamber that removes any trace of moisture.
At this point the oil can be filtered through fullers earth to remove any impurities and then it is pumped into the transformer under vacuum.
This is a complicated process, but it is well worth it as the transformer (after testing) can be placed in service for years without problems.
If anybody needs more info I can elaborate!
Thanks for reading !
Jerry