Taking apart a large transformer

Page 2 of 9  
Sorry for the old article followup, but it took awhile to get back to this...

Almost certainly that was due to contaminates that came with the PCBs, (PCDFs/furons or PCDDs/dioxins) not the PCBs themselves. Many, many studies have shown no acute toxicity from PCB exposure either dermal, inhaled or ingested.
Common table salt is toxic. Are you familar with LD50 and LC50 measures of toxicity? You cannot compare LD50 across species, and I don't know any PCBs LD50 for humans. The human LD50 for salt is about 3000mg/kg.
Oh, one other thing to note while reading studies on health affects, "toxic" does not mean fatal. It just means bad effect, eg http://www.greenfacts.org/glossary/tuv/toxic.htm
http://www.foxriverwatch.com/dermal_skin_pcb_pcbs_1e.html summarizes 31 studies, including multiple covering the incident in Japan to which you refer. The common conclusion is that PCB exposure is not fatal to humans and generally not fatal to animals (but different species show vastly different reactions).
''Clinical studies of the health effects of PCB exposure have shown that the skin is the only organ system affected by PCB exposure and that the skin disorders, primarily chloracne, occurred only in persons occupationally exposed to relatively high PCB concentrations. In contrast to experimental animal studies, other organ systems such as the liver and immune and hematopoietic systems of humans are not affected. The divergence between the effects observed in humans and animals may reflect differences in interspecies susceptibility and exposure. The authors conclude that there appears to be little basis for the concern for internal organ system toxicity, especially since use and disposal of PCBs is now strictly controlled. (James et al, 1993)''
and
''Both Yusho and Yu-Cheng specimens contained numerous isomers of trichlorinated and hexachlorinated dibenzofurans. The oils involved in both incidents contained similar compositions of PCQs; they appeared to have similar ratios of the six types of PCQ in their basic makeup. In general, Yusho and Yu-Cheng samples were composed of similar congeners; the tissue levels of PCQs, PCDFs, and PCBs remained elevated and clinical symptoms persisted for over 10 years. In occupationally PCB exposed workers, on the other hand, dermal lesions and other symptoms disappeared rapidly after discontinuation of PCB handling, although PCB levels remained high. The authors conclude that PCDFs and PCQs appear to be strongly associated with the development of Yusho and Yu-Cheng. (Miyata et al, 1985)''
sdb
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Didn't the new President of the Ukraine suffer from dioxin poisoning? It is said to have been fed to him by his political opponents. Gave him a hell of a case of chloracne that has completely disfigured him.
Tom
wrote:

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utility that has some experience with it.
Firstly, size doesn't matter, it was everywhere at one time, and ignoramus's original post did not mention if the transformer was dry or not. So I think Doug's response to be wary of PCBs was the right thing to suggest, given the possible dangers involved.
PCBs were the answer to a maidens prayer for transformer and capacitor manufacturers, since it had much better heat transfer characteristics combined with excellent dielectric strength. Plus it allowed more compact designs, and a cheaper overall product cost. All was well in transformer and capacitor land until a couple of incidents that drew attention to some of PCB environmental effects.
One incident, came about because PCBs look and smell remarkably like cooking oil, somewhere ( Japan I think ) a barrel of it found its way into a restaurant and it was used to cook food. A number people were hospitalised from its effects, burning of the mouth, throat etc.
Another incident involved a fire in a basement substation in a high rise building in the US. Although it is hard to burn, a fault in the transformer set it alight, and the buildings airconditioning system pumped the smoke from the fire through the building. PCB's produce dioxin when they burn, and the building was contaminated with dioxin. I'm not sure the mess has ever been cleaned up.
Once they started looking at the chemical, they found that it had the property of being very stable, and of accumulating in the food chain. If someone did dump it in a lake, it would still be in the lake 500 years later, most likely in the fish at the top of the food chain.
Experience in our own area was with a customer who bought us a sample capacitor to have tested. They had been asleep in bed, hot night with the fan on, when a capacitor in their ceiling fan leaked PCB's on to them. They had fairly serious skin reactions on their faces, necks, and legs, like a reaction to strong bleach, although the reaction was not immediate. The fellow who bought us the capacitor had the burns, so I've actually seen the effects of pure PCB.
We removed all our PCB capacitors from our network, and replaced them with non PCB types. We stockpiled these for disposal on an incinerator ship which cruised the world destroying the PCBs by burning them at exteremly high temperatures, to destroy the dioxin, out at sea, since it was too dangerous to attempt it on land. Funny thing was the ships kept sinking, the cynic in me thinks it must have been cheaper to load up an old ship to the gunnels with the suff, and sink it rather than actually burn it.
While we had no PCB transformers on our network, we acquired a network which did have some. The problem was that maintenance processes had cross contaminated a lot of other transformers with the stuff, and at one stage the EPA here had set a limit of 5 parts per million contamination of PCB before the oil was clasified as hazardous. I believe it is now at 20 ppm. I believe this to be a major over reaction to risks involved, it's the pure stuff that needs to be treated with respect.
While there is a fair bit of hysteria surrounding PCBs, there are some real risks with the pure stuff that people playing with old transformers and capacitors need to be wary of.
regards,
John
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Thanx for the warning, I was not aware that there still might som PCBs arround in old oil filled transformers and old capacitors so I'll keep that in mind next time I go shopping at the local scrapheap :-)
/Morten
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Just don't ever lose weight. Toxins are stored in your fat cells.

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Right. Same as the fish that are contaminated.

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Thank you for an extremely interesting article.
i
On Tue, 4 Jan 2005 10:13:33 +1100, john johnson

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I've heard OLD veteran teachers say they think there's something in the water - people no longer have reading comprehension skills. Luckily, you and two others here seem to escaped this fate.
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How about these huge capacitors from the demolished UPS?
See http://igor.chudov.com/tmp/capacitors/ The cup is pictured for size comparison. Are they 4.1 farad each or they are 4.1 millifarad? They are rated for 300V. Are there PCB in them? i
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Ignoramus22732 wrote:

The 'm' is a leftover from the olden days, when it meant 'micro', not the metric standard 'milli'. Milli is not used in capacitor rating. Pico, micro then Farads. New capacitors would be probably marked with the 'u' instead of 'm'
So, they are 4100 microfarad capacitors
They are rated for

I don't know. Maybe Tantalum or Aluminium oxide?
http://www.radio-electronics.com/info/data/capacitor/capacitor_types.php
These guys found an interesting use for them:
http://www.4hv.org/archive/topic.22395.html
mike
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I see. Thanks. I am curious, how do they make 1.2 FARAD capacitors that they sell for car music. It would seem that if they were made using the same technology, they would need to be like 250 times bigger than my capacitors!
i
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They make them thinner. Most electrolytics are composed of aluminum foil (possibly embossed, to increase surface area) wound in a spiral with a paper which holds an electrolyte. The aluminum is anodized and the aluminum oxide layer (which degrades in storage, and can be replenished by reforming the cap - taking up the voltage to rated value slowly) is the dielectric which holds the charge.
Your capacitors are actually higher in energy density than a low voltage type, based on the last size/voltage/energy comparison I did.
Tim
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Thanks, that makes complete sense. I also thought that X farad at 12 V vs. Yfarad at 250 V cannot be compared, what really matters (for some applications) is how much energy they can store for rated voltage.
i
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Energy stored in a capacitor E = 0.5 * C * V^2, so a 100uF cap charged to 100V stores a quarter of the energy of one charged to 200V. 1F charged to 16V = 128J stored. A capacitor charged to 250V storing the same energy would be 0.004F = 4mF = 4000uF (more exactly, F if that extended character shows up). Of course, the voltage and capacitance (among other specs) have other electrical importance, depending on use. :)
Tim
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Ignoramus28225 wrote: ...

They are electrolytic capacitors and use a carbon aerogel as one of the "plates". Aerogels have a very large surface area per volume.
Anthony
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If they are a metal can type they are most likely full of PCB oil unless stated otherwise on the metal cans.
I doubt they are 4 farads. More likely 4 microfarads uf.

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Maybe, if they are line voltage AC capacitors. If they are polarized, for DC or pulsed DC, with one terminal marked +positive and the other -negative, they are electrolytic capacitors, without PCBs.
Electrolytic capacitors have a conductive electrolyte in them, and if they leak they can cause a short. I had a television set damaged that way from a leaking electrolytic capacitor - ZAP!
CM
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If the electrolyte conducted it would be a resistor.

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Gymy Bob wrote:

You NEVER cease to amaze..
A few GymyBobisms..new additions daily: ===================================== At 11.6 volts a 12v battery is about 50-70% charged still.
Polish solar panels are what americans called "flashlights"
Propane will disapate and freeze when it evaporates.
Gasoline is not nearly as volatile as hydrogen.
Many people have browsers that economize the download
Let's say youre solar cell was trying to put out 14.3 volts DC and you stuck a 10 ohm meter in series with a charged 13.8 volt DC battery.
This is power grid induction through capacitive proximity
A thought I have is rain water from a roof on a three story home through a micro-turbine.
Breakers are good for one time usage of one fault and then they need to be replaced for any warrantied usage.
If the breaker interupts a fault, it should be replaced.No warranty will honoured after that.
I don't have a link at this time
There are no hydrogen molecules in water and the oxygen in water isn't flammable either.
NiCads and NiMh batterries are designed to take a current charge forever.
Did they have electricity back in 1994?
I have been around so long with this stuff I believe I invented the diode in 1941 but I am not familiar with the solar panel usage requirements of them. (no P & N substrate explanations please. I wrote the GE manual...LOL)
NOTE: do not pass ground wires through metal holes or cable clamps with two screws on a metal surface.
There is **NOT*** enough energy in a lightning bolt to power your house for more than an hour...if that. Do the math. The figures escape me but let's say it puts out a roughly MWatt of power for 100 nanoseconds? 100 x 10-9 x 1 x 106 / 3600 (sec/hr) = 0.0027 wH oooops.... Wouldn't light your home for a 1/2 second. OK..OK.. multiply the figures time 100 or 1000. Now it would light a 100W bulb for 1 second.
The IEEE-232 standards were never followed or known by many.
Fossil fuels are still renewable and being cxreated as we speak.
Children are venerially created.
If you want to discuss this then fine, otherwise go fuck yourself like your mother did.
Can you let go of my dick before it explodes on ya, goofball?
Petroleum is not related to Natural gas.
I would rather work at my $100/hour job than at chopping wood for hours to save $3/hour
I have no license, I wire and inspect other's wiring for a job and work for a medium size electrical utility.
The majority prefers top posting.
Get your tear ducts flushed by a knowledgeable optometrist.
Not many materials have the huge exponential resistance/heat curve aluminum does. Overload doesn't make it glow like copper...it flashes and explodes.
A bathroom fan motor would never push hot air down ten feet or cold up ten feet.
Bathroom fans have a hard time pushing 55 cfm through a 3-4" pipe 20 horizontal feet. They are made to vent smells and humid air horizontally only.
Why not spend the money on a contract with the grid company and get an exclusive line to your house and never have brownouts.
Usenet rules dictate top posting for readability
Many cell modems are set up to filter bottom posts out.
Cell modems do not cut off anything.
What security flaws. (refering to Outlook Express)
Bottom posting was the was in the 70s and 80s before threading browsers were available cheap (like OE)
What is a PMW?
10 pounds per gallon Imperial. That gallon is totally unique to the US....ooops..I think all gallons are unique to the US now.
The standard Imperial gallon the whole world used weighs 10 pounds exactly.
The copper isn't worth more than 5 cents per pound. It is classed a mixed copper and nobody wants it.
Hey moron! The copper is considered "mixed" copper and is worth about $0.02 per pound, if he seperates it all.
Just don't ever lose weight. Toxins are stored in your fat cells.
Did you know, **NO***, I repeat ***NO*** death has ever been related to PCBs?
Insulated square copper wires from a dry transformer are not 99% copper and take a lot of work to remove the insulation.
I have tonnes of insulated copper wire if you want it. I think you could almost have for the picking it up. How many bins can you take per year
Can't this tranformer be used by somebody to generate a second 120V from a single phase 120V inverter? It sounds pretty beefy.
BTW: once you knock the wedge out of the coil form the laminations will be easier to get out. This keeps them from buzzing until the varnish and other impregnations go into it.
All you guys have a bad Christmas or Jewish and didn't see Santa or something?
Run each signal twisted with a ground for noise. RD twisted with gnd as a pair, TD twisted around ground as a pair etc... This means signal/logic ground not power ground or case ground, if they are different. Do not connect the other ends of the ground conductors.
Tar pitch in a flourescent ballast does ***NOT*** contain PCBs and probably never did.
Religion is not genetic or even herodigious
I believe the warmest part of the lake is just below the ice. As the water frezes it rises to the top and joins the other ice formations.
Gel cell won't cut it when it comes to putting out 100A or more. They cook in ne spot and the rest of the electrolyte doesn't circulate fast enough
If the electrolyte conducted it would be a resistor.
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