What happens when I connect power to an MOT electromagnet?

Discussion in 'General Science' started by joshp, May 10, 2016.

  1. joshp

    Thread Starter New Member

    May 10, 2016
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    Hello Guys,
    This is my first post so forgive me if its in the wrong section. I made a microwave transformer electromagnet for a robot I am making. i removed the secondary and all that and just left the primary. The primary coil is about 1/2 in below the top (not resting on the bottom of the "U"). When i connect a 9v battery to it, the coil ends spark but the entire transfomer does not seem to get magnetized. Could anyone help me? Thanks a lot.
     
  2. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    A 9-V battery won't give anywhere near the current line voltage will give. For a strong electromagnet, you need amps.

    John
     
  3. joshp

    Thread Starter New Member

    May 10, 2016
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    Oh, ok. So how many amps are appropriate? I would like if it could be supplied by an onboard battery.
     
  4. jpanhalt

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    What was your MOT rated for in watts? 1000W's? That is a little over 9 A a 110 volts. You cannot get that with a 9-V battery!

    John
     
  5. joshp

    Thread Starter New Member

    May 10, 2016
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    Yeah, it was 1000W. So I'll need to redo my robot design, or ill just use another lifting device. Thanks for helping. Two more questions, though (sorry for asking so much). When i do connect my design (im going to ask my electrician friend to make a circuit) to the sufficient power supply, should it become hot since essentially it is a short circuit around a steel core? Also, my MOT primary coil seems to have some sort of glue on all the wires in the coil, sort of like an insulation. Should I remove that and try again?
     
  6. jpanhalt

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    Don't forget about the effect of inductance in an AC circuit. Presumably, your MOT ran on 50 or 60 Hz. A competent DC source of the same voltage would yield very different, even catastrophic results. Measure the DC resistance of the coil. That will give you can indication of the ultimate DC current.

    I don't think it is something you should be fooling with without some appreciation of the difference between AC and DC.

    John
     
  7. joshp

    Thread Starter New Member

    May 10, 2016
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    Ok, then. I won't mess around with that. One last question. If i theoretically connected a powerful enough DC supply to this, would it work? Or would i have to remove the glue/insulation first?
     
  8. jpanhalt

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    A sufficiently powerful DC supply would probably melt the wires, perhaps spectacularly. You need to read about how transformers work.

    John
     
  9. joshp

    Thread Starter New Member

    May 10, 2016
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    Sorry if i was not clear, but i meant the magnet made from the transformer. If i connected a sufficiently powerful DC supply to my transformer magnet, would it work? Or should i remove the insulation first? Or would it still melt, although a current is sent through a wire around a steel core? Thanks so much for helping me.
     
  10. jpanhalt

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    Why would you remove the insulation?

    You are talking about something potentially dangerous and apparently have little experience with appropriate safety measures, such as fuses. What current to you expect? What gauge is the wire? What size fuse do you have in the circuit? MOT's are designed for AC do not apply the same DC voltage!

    John
     
  11. joshp

    Thread Starter New Member

    May 10, 2016
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    Ok. :( I'll find another way. Thanks for helping me. I don't want to play with something dangerous. I'll just buy an electromagnet from Amazon.
     
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