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10 Comments


  1. Cool vid. Thanks for that. Interesting that the low voltage “coil” is a massive plate rolled up like that.

    I wonder what kind of capacitance that throws into the system?

    Cheers


  2. Hey Jacob,

    I was also surprised to see a simple wrapping of aluminum instead of actual wire. Probably has some impact. I am sure it is much cheaper to produce but must have some impact on performance and quality of output.


  3. Very interesting video. I was surprised by the aluminum sheet too. I think it’s mainly to handle the huge current that is produced on the low voltage side. Aluminum is a very good conductor, the third best after silver and copper. It is often used for power lines instead of copper because of its lower price.
    I wouldn’t worry too much about parasitic capacitance. A (very) rough estimate gives me 5nF, but since it’s part of the same sheet it’s completely short-circuited.
    The magnetic circuit looks high quality, with a large number of thin sheets of steel to reduce induced currents. Efficiency and low losses are probably a high priority when handling the kind of power that goes through these transformers.


  4. Wow, that’s pretty cool.

    I have to agree with Vic, capacitance would be low as it is one large sheet., not seperate sheets.


  5. At 60Hz, 5nF (I’m taking Vic’s word on that one) would create a reactance of -530k, which would definitely be negligible in parallel with a friggin giant sheet of Al.

    Not only that, but any capacitance in the system would be *good*, since the utility companies promptly hang more capacitors off the side of transformers. This is because most of the loads their serving are more inductive than capacitive (i.e. motors), and you want to maximize your power factor (by canceling the inductive loads with capacitive loads, since neither take real power). The Wikipedia article on power factor explains this nicely.


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