Taking apart a large transformer

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Ah, thanks for driving the point home. Will killfile in due course (even if only a blow-in in just this thread).
Tim
-- "I've got more trophies than Wayne Gretsky and the Pope combined!" - Homer Simpson Website @ http://webpages.charter.net/dawill/tmoranwms
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Gymy Bob wrote:

Bob, Bob, Bob....
It does conduct. I know it conducts because I've had to clean and repair hardware where a capacitor burped up electrolyte onto circuitry. Circuitry that didn't work anymore because the electrolyte was conducting.
Please stop guessing.

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Geee. I would take a few brain cells to conclude your cap was defective if it burped. Ya' think that would be cause you have conductive electrolyte? Maybe the electrolyte was full of carbon after the internal fault?
Go back and take some very basic electronics, or maybe just study some. Electrolytes are not conductors of electricity in a capacitor.
OK.. let's start at the beginning. A capacitor is two conductive metal plates separated by an insulating medium. Now add electrolyte. Did ya' get a resistor? Ever put your ohmmeter (do I need to explain an ohmmeter also?) across a capacitor? It measures infinity after charging to the supply voltage because the electrolyte is an insulator.
See how that works? That wasn't too hard. Was it? Now try to remember for next time. Are you an electrician too?
If you want to be insulting, make sure it isn't yourself you are ridiculing.

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Gymy Bob wrote:

You truly amaze. This is the second bit of misinformation in just a few hours. Electrolytes make pretty GOOD conductors. That's probably WHY they are called electrolytes. Now, sometimes we DON'T want current to flow, so the **DIELECTRIC** was invented.
In some (all?) electrolytic caps, the dielectric is an oxide layer.. This is a very thin layer that allows good storage capacity in a smaller physical size. The conductive electrolyte makes up the negative side of the thing.
http://www.tpub.com/neets/book2/3f.htm
How does it feel to know so much and be WRONG about all of it?
mike
--
The trouble with people is not that they don't know but that they know so
much that ain't so.
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Gymy Bob wrote:

But it wasn't, Bob. Read on...

Um, yes they are.

It reads infinity because there's an oxide layer on the anode. Oxide, at least in this case, is an insulator.

I can play with the big wires or the small wires. Same electrons either way.

Trying real hard not to...
here's a quote from the Elna capacitor website at:
http://www.elna.co.jp/en/ct/c_al01.htm
Aluminum electrolytic capacitors are made by layering the electrolytic paper between the anode and cathode foils, and then coiling the result. The process of preparing an electrode facing the etched anode foil surface is extremely difficult. Therefore, the opposing electrode is created by filling the structure with an electrolyte. Due to this process, the electrolyte essentially functions as the cathode. The basic functional requirements for the electrolyte are as follows: (1)      Chemically stable when it comes in contact with materials used in the anode, cathode, and electrolytic paper. (2)      Easily wets the surfaces of the electrode. (3)      Electrically conductive. (4)      Has the chemical ability to protect the anode oxide thin film and compensate for any weaknesses therein. (5)      Low volatility even at high temperatures. (6)      Long-term stability and characteristics that take into consideration such things as toxicity.
Take a look at #4, Bob. It says that electrolyte is electrically conductive.

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Yup, I got that one wrong. You were correct. Sorry. Wrong technology. Thanx for that information and correction!

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wrote:

When electrolytic caps short is is due to "thorns" growing on the plates and punching through, shorting the plates together. Then they heat up and blow. When they go, they often take out other components around them.
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snipped-for-privacy@sny.der.on.ca wrote:

before. Mind you its a long time since I studied the internal behaviour of components in detail.
Is it even possible to redeposit metallic Aluminium by electrolysis from an aqueous solution?
I strongly suspect you are confusing it with the common failure mechanism for NiCd cells.
Electrolytics commonly develop a reduced capacitance, increased leakage current and a higher ESR (effective series resistance) then heat up and vent or blow due to internal gas or even steam pressure. Exactly what is going on during this process, I dont know in detail, but I've replaced enough of them to be VERY familiar with the results :-)
--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk [at]=@, [dash]=- &
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Ignoramus22732 wrote:

The historical aspect of this just HAS to be remembered.
================================================Only metric prefixes for 10+6 or more have an upper-case abbreviation (e.g., M = 10+6, G = 10+9, etc.). In particular, note that the prefix m indicates 10-3 and M indicates 10+6. The difference between an upper-case M and a lower-case m is nine orders of magnitude! One should be warned that American manufacturers of capacitors often use "mF" or "MF" to indicate microfarads, a practice that is both incorrect and misleading.
http://www.rbs0.com/tw.htm ================================================
mike
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I agree, it is a holy mess. m stands for milli. u stands for micro. n stands for nano.
i

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Only because most cannot type Greek characters on their computers. The prefixes are Greek letters designated by some standards committee.
wrote:

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These seem to be electrolytic capacitors rather than the oil filled type -- no PCBs.
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three oil filled AC paper caps in the picture behind the bank of blue electros would be prime contenders for PCB, but unlikely if manufactured 1990.
--
Regards, Chas.


To Email, replace 'xxx' with tango papa golf.
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Those do say that they do not contain PCB.
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Yes, definitly "Reactionay" in that you had NO Knowledge of the transformer in question, and when others explained that ALL these used in a FerroUPS, are DRY transformers, you still insist telling the world, your prepositioned agenda. Actually, some of US do know exactly what transformer the OP has, and what type it is, and that it doesn't have anything to do with PCB's. Now, do you know what PCB stands for, or is this another area that you knowledge base doesn't cover?
Me
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wrote:

You will notice that my suggestion was posted before any of these explanations arrived. Or, perhaps you won't notice.
In any case, it doesn't matter to you, really. You know that.
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Nope. The chemicals were there to facilitate heat transfer, especially in larger grid transformers. Needless to say, non-conductive liquids with a high boiling point are required for the task.
<http://www.ehso.com/EHSO_PCB.htm
Characteristics and Uses of PCBs
PCBs belong to a family of organic compounds known as chlorinated hydrocarbons. Key characteristics include: high boiling point, high degree of chemical stability, low flammability, and low electric conductivity. Between 1926-29 and 1977, PCB-containing products were manufactured for use in applications where stable, fire-resistant, heat-transfer properties were demanded. The most extensive use of PCBs occurred in dielectric fluids. Such fluids typically have the following characteristics: a heavy oil appearance, high boiling point, high chemical stability, high flash point, low electrical conductivity, and low water solubility. PCBs were also used as plasticizers and additives in lubricating and cutting fluids. Most PCBs were sold for use as dielectric fluids (insulating liquids) in electric transformers and capacitors. Other uses included heat transfer fluid, hydraulic fluid, dye carriers in carbonless copy paper, plasticizers in paints, adhesives, and caulking compounds, and filters in investment casting wax. Although PCBs are no longer commercially made in the United States, many electric transformers and capacitors once filled with PCBs are still in service. Additionally, PCBs currently are being inadvertently produced as byproducts during the manufacture of certain organic chemicals. PCB Manufacturers and Trade Names lists some of the manufacturers, who made PCBs and the trade names of their products.
Why Are PCBs Harmful to Human Health and the Environment When released into the environment, PCBs do not easily break apart and form new chemical arrangements (i.e., they are not readily biodegradable). Instead they persist for many years, bioaccumulate, and bioconcentrate in organisms. Well documented tests on laboratory animals show that various levels of PCBs cause reproductive effects, gastric disorders, skin lesions, and cancerous tumors. Exposure to PCBs in humans can cause chloracne (a painful, disfiguring skin ailment), liver damage, nausea, dizziness, eye irritation, and bronchitis.
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All minor ailments and no deaths have ever been attributed to it.
Did you wash your hair in detergent this week?
wrote:

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wrote:

You may consider it a "minor ailment", but have you seen the photos of that Ruskie politician who was purportedly poisoned with dioxin? A year ago he looked about like baby faced John Edwards, now he looks more like a puffy faced, acne ridden Andy Rooney...
DJ
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I thought we were talking PCBs?

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