Everything You Wanted To Know About Transformers (But Were Afraid To Ask)

[Jim Pytel] has a lot of very good instructional videos on his channel, and he recently added one you’ll enjoy on transformers. You probably know that transformers convert one AC voltage into another AC voltage. Some step up voltage, some step down voltage, and others simply pass voltage through but isolate the input from the output.

The 40 minute video covers basics including how the transformer works, the meaning of the turns ratio, and how transformers reflect impedance. You probably should understand how to compute AC power, but if you need a refresher [Jim] has a video for that, too.

The video focuses mostly on power transformers, but many of the same concepts apply to signal transformers, too. We’ve always thought it is interesting that a transformer is just a generator where the rotating magnetic field is generated electrically instead of through shaft rotation. Or, if you prefer, a generator is just a transformer with a rotating magnet replacing the primary.

[Jim] promises to cover non-ideal transformers in a later video, but for this one, the transformers are ideal. That means the power output is the same as the power input, which would be nice, but isn’t realistic. Real transformers lose some power due to a variety of factors and there’s a lot of science behind coil winding and core material to minimize those losses to the extent practical.

If you want our take on transformers, we did that a while ago. If you think transformers are always magnetic, though, think again.

18 thoughts on “Everything You Wanted To Know About Transformers (But Were Afraid To Ask)

  1. I’ve been in some of the largest transformers in the world.
    The work that is involved getting a transformer ready is amazing.
    About 10 years ago I was working at Nanaco in ontario. Yes the old coal generating plant.
    I was inside these beast for 6 months getting them certified for operation.
    There were 3 of them. And 2 smaller ones at around 200,000 volts.
    There is nothing small about them. On the inside and outside.
    500,000 volts Cant remember the amperage but at that voltage who cares.
    As big as they were, me being a small person got me the job.
    These beast were about 35′ wide 45′ long and 30′ high. Its like crawling into a tank but bigger.
    And just thinking of the power that will be going threw them. Just Mind blowing.
    I think one of the funny parts is that, I was amazed at how much cleaning needs to be done on the insides.
    Clean Clean And more Cleaning. You have a part that needs to go in and it takes 3 to 5 men to get it in the hatch and there are only me and another person to move these 150lb – 200lb parts into place.
    Oh I miss those days.

    It really was a wast not converting them to gas.
    The only thing I know for sure is Our Government Really Knows How To Screw Things Up.
    Not saying any names…Premier Kathleen Wynne

    Good story thank for the memories.

    1. “And just thinking of the power that will be going threw them. Just Mind blowing.”

      I had a similar moment of thought when I had my head squeezed between two 3-ph 2000A 11kV bus bars trying to attach clamps either side of a current transformer to calibrate it. I was thinking “If these power up right now they’ll be cleaning my brain juice off the sides for weeks”.

      1. I was once visiting a 20kv station of a mid range industrial plant.


        Scary to the bones. Bus bars with 20kv and >100A…. And a small fence between me and THAT! Just use a vacuum cleaner to collect my remains.

        I sunk my hand deeeeeep into my work clothes and sermonize “you can’t touch anything” to myself. ALL. THE. TIME.

    2. It’s Nanticoke not Nanaco.. formerly run by Ontario Power Generation.
      Massive coal fired plant. Also my home town.
      My first job as a boilermaker was here climbing inside these massive 150ft+ high boilers to repair the tubes.
      Very cool plant to wander around.

  2. There is a rotating magnetic field in a static transformer ? Varying yes but not rotating, and the only reason the magnetic field in a motor or generator may be rotating is that rotation is the essence of those machines.

  3. When I was a kid, I had lots of fun with Transformers. The kid across the street hat Optimus Prime, but I was lucky to find Ultra Magnus on a flea market, which is in my eyes far superior.

    1. I used to build Heathkits back in the day…

      But I do recall seeing some news headline, late ’80s I think that said something like, “Transformers are the most popular Christmas gift this year.” I thought like wow, is kit building coming back in fashion? Are kids today once again fascinated by radio?

      Then I read the article and was most disappointed and realized I was way out of touch.

  4. So say I have a step up transformer and I was to switch it from running off of a separate power source to running off of the power coming out of the transformer, making it 100% self sufficient and not relying on anything but itself to run it!?

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