how the thermostat of an electrical rice cooker works ?

Discussion in 'General Electronics Chat' started by ranatungawk, Aug 6, 2011.

  1. ranatungawk

    Thread Starter Senior Member

    Oct 30, 2008
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    0
    Hi;

    Does any body knows how the thermostat of an electrical rice cooker works ? I found that there were only a spring and a magnet inside the sensor (see the pic). Basically I know that electrical rice-cooker works on the “water’s Latent heat” theory. How it sense 100C with only a magnet and a spring ? there were no any Bi-metal parts either …:confused:
     
  2. Kermit2

    AAC Fanatic!

    Feb 5, 2010
    3,772
    931
    Just a guess.

    Magnets can lose their magnetism at elevated temperature, allowing the spring to overcome the magnetic attraction, when things cool down the magnet again attracts the metal lever and the heating element turns on, until a high enough temp is reached to start the whole cycle again.
     
  3. sceadwian

    New Member

    Jun 1, 2009
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    Sorry Kermit, but this is incorrect. Magnets do lose their magnetism at elevated temperatures, but this is permanent it does not regain it when it cools. What is occurring is the spring itself is reaching it's Currie point and becoming paramagnetic, the magnetic field from the permanent magnet is still there, the spring is just no longer affected by it and will exert it's force, when the spring cools bellow it's Currie point it regains it's ferromagnetic properties and is attracted by the magnet again.
     
  4. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    I was 99.9% confident it was a heat/magnetism operation thing.

    Thanks for the correction... :)
     
  5. sceadwian

    New Member

    Jun 1, 2009
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    Thank you for sparking my interesting in correcting it =) I learn from others mistakes as much as my own.
     
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