Why does my transformer get burning hot when not in use?

I have a transformer from a microwave. A few of them. I replaced the secondary windings on them for my own nefarious purposes. I am having a problem with the primary windings getting extremely hot when I am not drawing any current from it at all, basically when it's idle, but plugged in. When i connect the secondary to a load it actually runs cooler. I feel like there is some component missing. Any advice would be greatly appreciated.

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  • 2 months ago
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    you wound the new secondary incorrectly, or you have shorted turns. or you have too high a voltage for the insulation, and you are getting arcing. 

    no load and the secondary voltage is higher, and you get more arcing, more losses. 

  • Anonymous
    2 months ago

    Make sure you correctly wired your transformer. Also, make sure you are not inputting more power than what the transformer is rated for.  

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  • 2 months ago

    Check to see if it is oscillating at high frequencies.

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  • 2 months ago

    Sounds like the primary is running at a Voltage higher than its rating. That's about the only thing that would increase the heating.

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  • 2 months ago

    The heat comes from iron loss and copper loss that are existed from most transformer. Microwave oven transformer was designed ever running in idling all the time

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  • Anonymous
    2 months ago

    < I replaced the secondary windings on them for my own nefarious purposes >

     

    You screwed up.

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