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Benutzer102023
9 months ago

Hi, actually quite simple, the switch with the bimetal is in series with the heating prism of the kettle. If the water is now hot, the bimetal bends, opens the switch, and the current supply to the heating spiral is interrupted.

Depending on how it is built, the counter would close again when the water is cooled and it heats again.

Adrian1970
9 months ago

The bimetal control of an electric kettle is based on a bimetal strip which consists of two different metals with different coefficients of expansion.

A bimetal strip consists of two mutually joined metals, which expand differently when heated. Typically, metals such as steel and brass or copper are combined.

When the water heater is switched on, the water and thus also the bimetal strip are heated. The metal with the higher coefficient of expansion (e.g. brass) expands more than the metal with the lower coefficient of expansion (e.g. steel).

The bimetal strip bends due to the different expansion of the metals. The side with the more strongly expanding metal arches outwards.

The bent bimetal strip is positioned in such a way that it activates a switch when a certain temperature is reached (typically 100° C. for boiling water). This switch is integrated into the electric circuit of the kettle.

When the bimetal strip is sufficiently bent, it presses on the switch and thereby interrupts the current flow to the heating element. This switches off the kettle and prevents further heating of the water.

When the water heater is switched off and the water cools, the bimetal strip returns to its original shape, as the temperature drops.

After cooling, the kettle could theoretically be switched on again when the bimetal strip releases the switch. However, many kettles have additional safety mechanisms that need to be manually reset to prevent accidental reheating.