how the thermostat of an electrical rice cooker works ?

Thread Starter

ranatungawk

Joined Oct 30, 2008
198
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:
 

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Kermit2

Joined Feb 5, 2010
4,162
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.
 

sceadwian

Joined Jun 1, 2009
499
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.
 
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